v3.26.1
Shareholder Report, Line Graph (Details) - USD ($)
 6 Months Ended 12 Months Ended 24 Months Ended 36 Months Ended 48 Months Ended 60 Months Ended 72 Months Ended 84 Months Ended 96 Months Ended 108 Months Ended 120 Months Ended
May 31, 2016
May 31, 2026
May 31, 2017
May 31, 2018
May 31, 2019
May 31, 2020
May 31, 2021
May 31, 2022
May 31, 2023
May 31, 2024
May 31, 2025
May 31, 2026
C000142693 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Investor Class Shares - Including sales charges                    
Accumulated Value $ 9,450   $ 10,086 $ 10,173 $ 9,923 $ 6,733 $ 9,068 $ 12,021 $ 11,599 $ 15,900 $ 19,489 $ 24,383
C000142692 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Class I Shares                    
Accumulated Value 10,000   10,691 10,806 10,567 7,186 9,698 12,895 12,467 17,109 21,036 26,361
C000142691 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Class C Shares - Including sales charges                    
Accumulated Value 10,000   10,582 10,589 10,255 6,891 9,215 12,130 11,615 15,789 19,218 23,856
C000142690 [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Class A Shares - Including sales charges                    
Accumulated Value 14,175   15,129 15,247 14,873 10,086 13,591 18,024 17,369 23,803 29,194 36,491
Alerian MLP C000142691 Index [Member]                        
Account Value [Line Items]                        
Accumulated Value 10,000   10,624 10,230 10,115 6,601 9,482 12,091 13,039 17,653 20,344 25,355
Cushing MLP Premier Tiered C000142691 Index [Member]                        
Account Value [Line Items]                        
Accumulated Value 10,000   10,624 10,230 10,115 6,601 9,079 11,876 11,056 14,932 19,122 24,144
Alerian Midstream Energy Select C000142691 Index [Member]                        
Account Value [Line Items]                        
Accumulated Value 10,000   11,620 11,520 11,727 8,672 12,626 16,515 15,375 20,765 26,592 33,575
Russell 3000 C000142691 Index [Member]                        
Account Value [Line Items]                        
Accumulated Value 10,000   11,769 13,542 13,880 15,471 22,264 21,444 21,880 27,916 31,578 40,876
Morningstar Energy Limited Partnership Category Average [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Morningstar Energy Limited Partnership Category Average                    
Alerian MLP Index [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Alerian MLP Index                    
Accumulated Value 15,000   15,935 15,345 15,173 9,902 14,222 18,137 19,558 26,480 30,516 38,033
Cushing MLP Premier Tiered Index [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Cushing MLP Premier Tiered Index                    
Accumulated Value 15,000   15,935 15,345 15,173 9,902 13,619 17,813 16,584 22,398 28,683 36,217
Alerian Midstream Energy Select Index [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Alerian Midstream Energy Select Index                    
Accumulated Value 15,000   17,430 17,279 17,590 13,008 18,939 24,772 23,063 31,148 39,888 50,363
Russell 3000 Index [Member]                        
Account Value [Line Items]                        
Line Graph and Table Measure Name   Russell 3000®Index                    
Accumulated Value $ 15,000   $ 17,654 $ 20,313 $ 20,820 $ 23,206 $ 33,397 $ 32,166 $ 32,821 $ 41,874 $ 47,367 $ 61,314