v3.26.1
Shareholder Report, Holdings (Details)
Apr. 30, 2026
C000159803 [Member]  
Holdings [Line Items]  
Percent of Total Investments 100.00% [1]
C000159803 [Member] | Petroleum Transportation And Storage Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.00% [1]
C000159803 [Member] | Diversified Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 12.00% [1]
C000159803 [Member] | Master Limited Partnerships [Member]  
Holdings [Line Items]  
Percent of Total Investments 16.00% [1]
C000159803 [Member] | Downstream Other [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.00% [1]
C000159803 [Member] | Upstream [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.00% [1]
C000159803 [Member] | Petroleum Transportation And Storage [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.00% [1]
C000159803 [Member] | Liquefied Natural Gas [Member]  
Holdings [Line Items]  
Percent of Total Investments 7.00% [1]
C000159803 [Member] | Electric LDC And Power [Member]  
Holdings [Line Items]  
Percent of Total Investments 14.00% [1]
C000159803 [Member] | Natural Gas Pipelines [Member]  
Holdings [Line Items]  
Percent of Total Investments 23.00% [1]
C000159803 [Member] | Diversified [Member]  
Holdings [Line Items]  
Percent of Total Investments 29.00% [1]
C000159803 [Member] | Common Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 84.00% [1]
C000159801 [Member]  
Holdings [Line Items]  
Percent of Total Investments 100.00% [2]
C000159801 [Member] | Petroleum Transportation And Storage Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 4.00% [2]
C000159801 [Member] | Diversified Securities [Member]  
Holdings [Line Items]  
Percent of Total Investments 12.00% [2]
C000159801 [Member] | Master Limited Partnerships [Member]  
Holdings [Line Items]  
Percent of Total Investments 16.00% [2]
C000159801 [Member] | Downstream Other [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.00% [2]
C000159801 [Member] | Upstream [Member]  
Holdings [Line Items]  
Percent of Total Investments 1.00% [2]
C000159801 [Member] | Petroleum Transportation And Storage [Member]  
Holdings [Line Items]  
Percent of Total Investments 5.00% [2]
C000159801 [Member] | Liquefied Natural Gas [Member]  
Holdings [Line Items]  
Percent of Total Investments 7.00% [2]
C000159801 [Member] | Electric LDC And Power [Member]  
Holdings [Line Items]  
Percent of Total Investments 14.00% [2]
C000159801 [Member] | Natural Gas Pipelines [Member]  
Holdings [Line Items]  
Percent of Total Investments 23.00% [2]
C000159801 [Member] | Diversified [Member]  
Holdings [Line Items]  
Percent of Total Investments 29.00% [2]
C000159801 [Member] | Common Stock [Member]  
Holdings [Line Items]  
Percent of Total Investments 84.00% [2]
[1]
Percentage of total investments as of April 30, 2026.
[2] Percentage of total investments as of April 30, 2026.