Shareholder Report, Holdings (Details)	Jun. 30, 2026
Class A \| Electric
Holdings [Line Items]
Percent of Net Asset Value	43.20%
Class A \| Midstream
Holdings [Line Items]
Percent of Net Asset Value	15.10%
Class A \| Railways
Holdings [Line Items]
Percent of Net Asset Value	14.90%
Class A \| Airports
Holdings [Line Items]
Percent of Net Asset Value	7.70%
Class A \| Gas Distribution [Member]
Holdings [Line Items]
Percent of Net Asset Value	5.70%
Class A \| Marine Ports
Holdings [Line Items]
Percent of Net Asset Value	4.30%
Class A \| Communications
Holdings [Line Items]
Percent of Net Asset Value	3.60%
Class A \| Toll Roads
Holdings [Line Items]
Percent of Net Asset Value	3.00%
Class A \| Environmental Services
Holdings [Line Items]
Percent of Net Asset Value	2.80%
Class A \| Other (includes short-term investments)
Holdings [Line Items]
Percent of Net Asset Value	(0.30%)
Class A \| UNITED STATES
Holdings [Line Items]
Percent of Net Asset Value	60.50%
Class A \| CANADA
Holdings [Line Items]
Percent of Net Asset Value	7.80%
Class A \| AUSTRALIA
Holdings [Line Items]
Percent of Net Asset Value	4.00%
Class A \| JAPAN
Holdings [Line Items]
Percent of Net Asset Value	3.70%
Class A \| SPAIN
Holdings [Line Items]
Percent of Net Asset Value	3.40%
Class A \| INDIA
Holdings [Line Items]
Percent of Net Asset Value	3.20%
Class A \| UNITED KINGDOM
Holdings [Line Items]
Percent of Net Asset Value	2.70%
Class A \| BRAZIL
Holdings [Line Items]
Percent of Net Asset Value	2.60%
Class A \| PHILIPPINES
Holdings [Line Items]
Percent of Net Asset Value	2.50%
Class A \| Other (includes short-term investments)
Holdings [Line Items]
Percent of Net Asset Value	9.60%
Class A \| NextEra Energy, Inc.
Holdings [Line Items]
Percent of Net Asset Value	5.50%
Class A \| Williams Cos., Inc.
Holdings [Line Items]
Percent of Net Asset Value	5.20%
Class A \| TC Energy Corp.
Holdings [Line Items]
Percent of Net Asset Value	4.90%
Class A \| Entergy Corp.
Holdings [Line Items]
Percent of Net Asset Value	4.70%
Class A \| Union Pacific Corp.
Holdings [Line Items]
Percent of Net Asset Value	4.50%
Class A \| CSX Corp.
Holdings [Line Items]
Percent of Net Asset Value	4.20%
Class A \| American Electric Power Co., Inc.
Holdings [Line Items]
Percent of Net Asset Value	3.00%
Class A \| National Grid PLC
Holdings [Line Items]
Percent of Net Asset Value	2.70%
Class A \| Norfolk Southern Corp.
Holdings [Line Items]
Percent of Net Asset Value	2.60%
Class A \| Targa Resources Corp.
Holdings [Line Items]
Percent of Net Asset Value	2.60%
Class C \| Electric
Holdings [Line Items]
Percent of Net Asset Value	43.20%
Class C \| Midstream
Holdings [Line Items]
Percent of Net Asset Value	15.10%
Class C \| Railways
Holdings [Line Items]
Percent of Net Asset Value	14.90%
Class C \| Airports
Holdings [Line Items]
Percent of Net Asset Value	7.70%
Class C \| Gas Distribution [Member]
Holdings [Line Items]
Percent of Net Asset Value	5.70%
Class C \| Marine Ports
Holdings [Line Items]
Percent of Net Asset Value	4.30%
Class C \| Communications
Holdings [Line Items]
Percent of Net Asset Value	3.60%
Class C \| Toll Roads
Holdings [Line Items]
Percent of Net Asset Value	3.00%
Class C \| Environmental Services
Holdings [Line Items]
Percent of Net Asset Value	2.80%
Class C \| Other (includes short-term investments)
Holdings [Line Items]
Percent of Net Asset Value	(0.30%)
Class C \| UNITED STATES
Holdings [Line Items]
Percent of Net Asset Value	60.50%
Class C \| CANADA
Holdings [Line Items]
Percent of Net Asset Value	7.80%
Class C \| AUSTRALIA
Holdings [Line Items]
Percent of Net Asset Value	4.00%
Class C \| JAPAN
Holdings [Line Items]
Percent of Net Asset Value	3.70%
Class C \| SPAIN
Holdings [Line Items]
Percent of Net Asset Value	3.40%
Class C \| INDIA
Holdings [Line Items]
Percent of Net Asset Value	3.20%
Class C \| UNITED KINGDOM
Holdings [Line Items]
Percent of Net Asset Value	2.70%
Class C \| BRAZIL
Holdings [Line Items]
Percent of Net Asset Value	2.60%
Class C \| PHILIPPINES
Holdings [Line Items]
Percent of Net Asset Value	2.50%
Class C \| Other (includes short-term investments)
Holdings [Line Items]
Percent of Net Asset Value	9.60%
Class C \| NextEra Energy, Inc.
Holdings [Line Items]
Percent of Net Asset Value	5.50%
Class C \| Williams Cos., Inc.
Holdings [Line Items]
Percent of Net Asset Value	5.20%
Class C \| TC Energy Corp.
Holdings [Line Items]
Percent of Net Asset Value	4.90%
Class C \| Entergy Corp.
Holdings [Line Items]
Percent of Net Asset Value	4.70%
Class C \| Union Pacific Corp.
Holdings [Line Items]
Percent of Net Asset Value	4.50%
Class C \| CSX Corp.
Holdings [Line Items]
Percent of Net Asset Value	4.20%
Class C \| American Electric Power Co., Inc.
Holdings [Line Items]
Percent of Net Asset Value	3.00%
Class C \| National Grid PLC
Holdings [Line Items]
Percent of Net Asset Value	2.70%
Class C \| Norfolk Southern Corp.
Holdings [Line Items]
Percent of Net Asset Value	2.60%
Class C \| Targa Resources Corp.
Holdings [Line Items]
Percent of Net Asset Value	2.60%
Class I \| Electric
Holdings [Line Items]
Percent of Net Asset Value	43.20%
Class I \| Midstream
Holdings [Line Items]
Percent of Net Asset Value	15.10%
Class I \| Railways
Holdings [Line Items]
Percent of Net Asset Value	14.90%
Class I \| Airports
Holdings [Line Items]
Percent of Net Asset Value	7.70%
Class I \| Gas Distribution [Member]
Holdings [Line Items]
Percent of Net Asset Value	5.70%
Class I \| Marine Ports
Holdings [Line Items]
Percent of Net Asset Value	4.30%
Class I \| Communications
Holdings [Line Items]
Percent of Net Asset Value	3.60%
Class I \| Toll Roads
Holdings [Line Items]
Percent of Net Asset Value	3.00%
Class I \| Environmental Services
Holdings [Line Items]
Percent of Net Asset Value	2.80%
Class I \| Other (includes short-term investments)
Holdings [Line Items]
Percent of Net Asset Value	(0.30%)
Class I \| UNITED STATES
Holdings [Line Items]
Percent of Net Asset Value	60.50%
Class I \| CANADA
Holdings [Line Items]
Percent of Net Asset Value	7.80%
Class I \| AUSTRALIA
Holdings [Line Items]
Percent of Net Asset Value	4.00%
Class I \| JAPAN
Holdings [Line Items]
Percent of Net Asset Value	3.70%
Class I \| SPAIN
Holdings [Line Items]
Percent of Net Asset Value	3.40%
Class I \| INDIA
Holdings [Line Items]
Percent of Net Asset Value	3.20%
Class I \| UNITED KINGDOM
Holdings [Line Items]
Percent of Net Asset Value	2.70%
Class I \| BRAZIL
Holdings [Line Items]
Percent of Net Asset Value	2.60%
Class I \| PHILIPPINES
Holdings [Line Items]
Percent of Net Asset Value	2.50%
Class I \| Other (includes short-term investments)
Holdings [Line Items]
Percent of Net Asset Value	9.60%
Class I \| NextEra Energy, Inc.
Holdings [Line Items]
Percent of Net Asset Value	5.50%
Class I \| Williams Cos., Inc.
Holdings [Line Items]
Percent of Net Asset Value	5.20%
Class I \| TC Energy Corp.
Holdings [Line Items]
Percent of Net Asset Value	4.90%
Class I \| Entergy Corp.
Holdings [Line Items]
Percent of Net Asset Value	4.70%
Class I \| Union Pacific Corp.
Holdings [Line Items]
Percent of Net Asset Value	4.50%
Class I \| CSX Corp.
Holdings [Line Items]
Percent of Net Asset Value	4.20%
Class I \| American Electric Power Co., Inc.
Holdings [Line Items]
Percent of Net Asset Value	3.00%
Class I \| National Grid PLC
Holdings [Line Items]
Percent of Net Asset Value	2.70%
Class I \| Norfolk Southern Corp.
Holdings [Line Items]
Percent of Net Asset Value	2.60%
Class I \| Targa Resources Corp.
Holdings [Line Items]
Percent of Net Asset Value	2.60%
Class R \| Electric
Holdings [Line Items]
Percent of Net Asset Value	43.20%
Class R \| Midstream
Holdings [Line Items]
Percent of Net Asset Value	15.10%
Class R \| Railways
Holdings [Line Items]
Percent of Net Asset Value	14.90%
Class R \| Airports
Holdings [Line Items]
Percent of Net Asset Value	7.70%
Class R \| Gas Distribution [Member]
Holdings [Line Items]
Percent of Net Asset Value	5.70%
Class R \| Marine Ports
Holdings [Line Items]
Percent of Net Asset Value	4.30%
Class R \| Communications
Holdings [Line Items]
Percent of Net Asset Value	3.60%
Class R \| Toll Roads
Holdings [Line Items]
Percent of Net Asset Value	3.00%
Class R \| Environmental Services
Holdings [Line Items]
Percent of Net Asset Value	2.80%
Class R \| Other (includes short-term investments)
Holdings [Line Items]
Percent of Net Asset Value	(0.30%)
Class R \| UNITED STATES
Holdings [Line Items]
Percent of Net Asset Value	60.50%
Class R \| CANADA
Holdings [Line Items]
Percent of Net Asset Value	7.80%
Class R \| AUSTRALIA
Holdings [Line Items]
Percent of Net Asset Value	4.00%
Class R \| JAPAN
Holdings [Line Items]
Percent of Net Asset Value	3.70%
Class R \| SPAIN
Holdings [Line Items]
Percent of Net Asset Value	3.40%
Class R \| INDIA
Holdings [Line Items]
Percent of Net Asset Value	3.20%
Class R \| UNITED KINGDOM
Holdings [Line Items]
Percent of Net Asset Value	2.70%
Class R \| BRAZIL
Holdings [Line Items]
Percent of Net Asset Value	2.60%
Class R \| PHILIPPINES
Holdings [Line Items]
Percent of Net Asset Value	2.50%
Class R \| Other (includes short-term investments)
Holdings [Line Items]
Percent of Net Asset Value	9.60%
Class R \| NextEra Energy, Inc.
Holdings [Line Items]
Percent of Net Asset Value	5.50%
Class R \| Williams Cos., Inc.
Holdings [Line Items]
Percent of Net Asset Value	5.20%
Class R \| TC Energy Corp.
Holdings [Line Items]
Percent of Net Asset Value	4.90%
Class R \| Entergy Corp.
Holdings [Line Items]
Percent of Net Asset Value	4.70%
Class R \| Union Pacific Corp.
Holdings [Line Items]
Percent of Net Asset Value	4.50%
Class R \| CSX Corp.
Holdings [Line Items]
Percent of Net Asset Value	4.20%
Class R \| American Electric Power Co., Inc.
Holdings [Line Items]
Percent of Net Asset Value	3.00%
Class R \| National Grid PLC
Holdings [Line Items]
Percent of Net Asset Value	2.70%
Class R \| Norfolk Southern Corp.
Holdings [Line Items]
Percent of Net Asset Value	2.60%
Class R \| Targa Resources Corp.
Holdings [Line Items]
Percent of Net Asset Value	2.60%
Class Z \| Electric
Holdings [Line Items]
Percent of Net Asset Value	43.20%
Class Z \| Midstream
Holdings [Line Items]
Percent of Net Asset Value	15.10%
Class Z \| Railways
Holdings [Line Items]
Percent of Net Asset Value	14.90%
Class Z \| Airports
Holdings [Line Items]
Percent of Net Asset Value	7.70%
Class Z \| Gas Distribution [Member]
Holdings [Line Items]
Percent of Net Asset Value	5.70%
Class Z \| Marine Ports
Holdings [Line Items]
Percent of Net Asset Value	4.30%
Class Z \| Communications
Holdings [Line Items]
Percent of Net Asset Value	3.60%
Class Z \| Toll Roads
Holdings [Line Items]
Percent of Net Asset Value	3.00%
Class Z \| Environmental Services
Holdings [Line Items]
Percent of Net Asset Value	2.80%
Class Z \| Other (includes short-term investments)
Holdings [Line Items]
Percent of Net Asset Value	(0.30%)
Class Z \| UNITED STATES
Holdings [Line Items]
Percent of Net Asset Value	60.50%
Class Z \| CANADA
Holdings [Line Items]
Percent of Net Asset Value	7.80%
Class Z \| AUSTRALIA
Holdings [Line Items]
Percent of Net Asset Value	4.00%
Class Z \| JAPAN
Holdings [Line Items]
Percent of Net Asset Value	3.70%
Class Z \| SPAIN
Holdings [Line Items]
Percent of Net Asset Value	3.40%
Class Z \| INDIA
Holdings [Line Items]
Percent of Net Asset Value	3.20%
Class Z \| UNITED KINGDOM
Holdings [Line Items]
Percent of Net Asset Value	2.70%
Class Z \| BRAZIL
Holdings [Line Items]
Percent of Net Asset Value	2.60%
Class Z \| PHILIPPINES
Holdings [Line Items]
Percent of Net Asset Value	2.50%
Class Z \| Other (includes short-term investments)
Holdings [Line Items]
Percent of Net Asset Value	9.60%
Class Z \| NextEra Energy, Inc.
Holdings [Line Items]
Percent of Net Asset Value	5.50%
Class Z \| Williams Cos., Inc.
Holdings [Line Items]
Percent of Net Asset Value	5.20%
Class Z \| TC Energy Corp.
Holdings [Line Items]
Percent of Net Asset Value	4.90%
Class Z \| Entergy Corp.
Holdings [Line Items]
Percent of Net Asset Value	4.70%
Class Z \| Union Pacific Corp.
Holdings [Line Items]
Percent of Net Asset Value	4.50%
Class Z \| CSX Corp.
Holdings [Line Items]
Percent of Net Asset Value	4.20%
Class Z \| American Electric Power Co., Inc.
Holdings [Line Items]
Percent of Net Asset Value	3.00%
Class Z \| National Grid PLC
Holdings [Line Items]
Percent of Net Asset Value	2.70%
Class Z \| Norfolk Southern Corp.
Holdings [Line Items]
Percent of Net Asset Value	2.60%
Class Z \| Targa Resources Corp.
Holdings [Line Items]
Percent of Net Asset Value	2.60%

Shareholder Report, Holdings (Details)

Jun. 30, 2026