Shareholder Report, Holdings (Details)	Jun. 30, 2026
C000002899 \| NextEra Energy Inc.
Holdings [Line Items]
Percent of Net Asset Value	7.40%
C000002899 \| National Fuel Gas Co.
Holdings [Line Items]
Percent of Net Asset Value	6.20%
C000002899 \| American Electric Power Co. Inc.
Holdings [Line Items]
Percent of Net Asset Value	4.00%
C000002899 \| Evergy Inc.
Holdings [Line Items]
Percent of Net Asset Value	3.80%
C000002899 \| WEC Energy Group Inc.
Holdings [Line Items]
Percent of Net Asset Value	3.10%
C000002899 \| Southwest Gas Holdings Inc.
Holdings [Line Items]
Percent of Net Asset Value	3.00%
C000002899 \| Ameren Corp.
Holdings [Line Items]
Percent of Net Asset Value	2.90%
C000002899 \| The AES Corp.
Holdings [Line Items]
Percent of Net Asset Value	2.40%
C000002899 \| ONEOK Inc.
Holdings [Line Items]
Percent of Net Asset Value	2.30%
C000002899 \| Eversource Energy
Holdings [Line Items]
Percent of Net Asset Value	2.30%
C000002899 \| InvestmentType_Common Stocks
Holdings [Line Items]
Percent of Net Asset Value	95.00%
C000002899 \| InvestmentType_U.S. Government Obligations
Holdings [Line Items]
Percent of Net Asset Value	5.20%
C000002899 \| Utilities
Holdings [Line Items]
Percent of Net Asset Value	75.50%
C000002899 \| Other
Holdings [Line Items]
Percent of Net Asset Value	13.50%
C000002899 \| Communication Services
Holdings [Line Items]
Percent of Net Asset Value	6.00%
C000002899 \| U.S. Government Obligations
Holdings [Line Items]
Percent of Net Asset Value	5.20%
C000002899 \| Closed-End Funds
Holdings [Line Items]
Percent of Net Asset Value	0.00%
C000239633 \| NextEra Energy Inc.
Holdings [Line Items]
Percent of Net Asset Value	7.40%
C000239633 \| National Fuel Gas Co.
Holdings [Line Items]
Percent of Net Asset Value	6.20%
C000239633 \| American Electric Power Co. Inc.
Holdings [Line Items]
Percent of Net Asset Value	4.00%
C000239633 \| Evergy Inc.
Holdings [Line Items]
Percent of Net Asset Value	3.80%
C000239633 \| WEC Energy Group Inc.
Holdings [Line Items]
Percent of Net Asset Value	3.10%
C000239633 \| Southwest Gas Holdings Inc.
Holdings [Line Items]
Percent of Net Asset Value	3.00%
C000239633 \| Ameren Corp.
Holdings [Line Items]
Percent of Net Asset Value	2.90%
C000239633 \| The AES Corp.
Holdings [Line Items]
Percent of Net Asset Value	2.40%
C000239633 \| ONEOK Inc.
Holdings [Line Items]
Percent of Net Asset Value	2.30%
C000239633 \| Eversource Energy
Holdings [Line Items]
Percent of Net Asset Value	2.30%
C000239633 \| InvestmentType_Common Stocks
Holdings [Line Items]
Percent of Net Asset Value	95.00%
C000239633 \| InvestmentType_U.S. Government Obligations
Holdings [Line Items]
Percent of Net Asset Value	5.20%
C000239633 \| Utilities
Holdings [Line Items]
Percent of Net Asset Value	75.50%
C000239633 \| Other
Holdings [Line Items]
Percent of Net Asset Value	13.50%
C000239633 \| Communication Services
Holdings [Line Items]
Percent of Net Asset Value	6.00%
C000239633 \| U.S. Government Obligations
Holdings [Line Items]
Percent of Net Asset Value	5.20%
C000239633 \| Closed-End Funds
Holdings [Line Items]
Percent of Net Asset Value	0.00%
C000034315 \| NextEra Energy Inc.
Holdings [Line Items]
Percent of Net Asset Value	7.40%
C000034315 \| National Fuel Gas Co.
Holdings [Line Items]
Percent of Net Asset Value	6.20%
C000034315 \| American Electric Power Co. Inc.
Holdings [Line Items]
Percent of Net Asset Value	4.00%
C000034315 \| Evergy Inc.
Holdings [Line Items]
Percent of Net Asset Value	3.80%
C000034315 \| WEC Energy Group Inc.
Holdings [Line Items]
Percent of Net Asset Value	3.10%
C000034315 \| Southwest Gas Holdings Inc.
Holdings [Line Items]
Percent of Net Asset Value	3.00%
C000034315 \| Ameren Corp.
Holdings [Line Items]
Percent of Net Asset Value	2.90%
C000034315 \| The AES Corp.
Holdings [Line Items]
Percent of Net Asset Value	2.40%
C000034315 \| ONEOK Inc.
Holdings [Line Items]
Percent of Net Asset Value	2.30%
C000034315 \| Eversource Energy
Holdings [Line Items]
Percent of Net Asset Value	2.30%
C000034315 \| InvestmentType_Common Stocks
Holdings [Line Items]
Percent of Net Asset Value	95.00%
C000034315 \| InvestmentType_U.S. Government Obligations
Holdings [Line Items]
Percent of Net Asset Value	5.20%
C000034315 \| Utilities
Holdings [Line Items]
Percent of Net Asset Value	75.50%
C000034315 \| Other
Holdings [Line Items]
Percent of Net Asset Value	13.50%
C000034315 \| Communication Services
Holdings [Line Items]
Percent of Net Asset Value	6.00%
C000034315 \| U.S. Government Obligations
Holdings [Line Items]
Percent of Net Asset Value	5.20%
C000034315 \| Closed-End Funds
Holdings [Line Items]
Percent of Net Asset Value	0.00%
C000002898 \| NextEra Energy Inc.
Holdings [Line Items]
Percent of Net Asset Value	7.40%
C000002898 \| National Fuel Gas Co.
Holdings [Line Items]
Percent of Net Asset Value	6.20%
C000002898 \| American Electric Power Co. Inc.
Holdings [Line Items]
Percent of Net Asset Value	4.00%
C000002898 \| Evergy Inc.
Holdings [Line Items]
Percent of Net Asset Value	3.80%
C000002898 \| WEC Energy Group Inc.
Holdings [Line Items]
Percent of Net Asset Value	3.10%
C000002898 \| Southwest Gas Holdings Inc.
Holdings [Line Items]
Percent of Net Asset Value	3.00%
C000002898 \| Ameren Corp.
Holdings [Line Items]
Percent of Net Asset Value	2.90%
C000002898 \| The AES Corp.
Holdings [Line Items]
Percent of Net Asset Value	2.40%
C000002898 \| ONEOK Inc.
Holdings [Line Items]
Percent of Net Asset Value	2.30%
C000002898 \| Eversource Energy
Holdings [Line Items]
Percent of Net Asset Value	2.30%
C000002898 \| InvestmentType_Common Stocks
Holdings [Line Items]
Percent of Net Asset Value	95.00%
C000002898 \| InvestmentType_U.S. Government Obligations
Holdings [Line Items]
Percent of Net Asset Value	5.20%
C000002898 \| Utilities
Holdings [Line Items]
Percent of Net Asset Value	75.50%
C000002898 \| Other
Holdings [Line Items]
Percent of Net Asset Value	13.50%
C000002898 \| Communication Services
Holdings [Line Items]
Percent of Net Asset Value	6.00%
C000002898 \| U.S. Government Obligations
Holdings [Line Items]
Percent of Net Asset Value	5.20%
C000002898 \| Closed-End Funds
Holdings [Line Items]
Percent of Net Asset Value	0.00%

Shareholder Report, Holdings (Details)

Jun. 30, 2026