Alerian MLP C000142691 Index [Member] Cushing MLP Premier Tiered C000142691 Index [Member] Alerian Midstream Energy Select C000142691 Index [Member] Russell 3000 C000142691 Index [Member] Morningstar Energy Limited Partnership Category Average [Member] Alerian MLP Index [Member] Cushing MLP Premier Tiered Index [Member] Alerian Midstream Energy Select Index [Member] Russell 3000 Index [Member] Water Midstream [Member] Oil Field Services [Member] Upstream Corp [Member] Crude Oil And Refined Products [Member] Refiners [Member] Canadian Midstream [Member] Natural Gas Transportation And Storage [Member] Natural Gas Gatherers And Processors [Member] Large Cap MLP [Member] Large Cap Diversified C Corps [Member] ONEOK Inc [Member] Pembina Pipeline Corp [Member] TC Energy Corp [Member] MPLX LP [Member] Keyera Corp [Member] Plains GP Holdings LP Class A [Member] DT Midstream Inc [Member] Williams Cos Inc The [Member] Energy Transfer LP [Member] Targa Resources Corp [Member] C000142693 [Member] Investor Class C000142692 [Member] Class I C000142691 [Member] Class C C000142690 [Member] Class A Investment Type [Axis] Net Assets Investment Company Portfolio Turnover No Trading Symbol Flag