Significant Accounting Policies - Accrued Expenses and Other Payables (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Mar. 31, 2017
Accounting Policies [Abstract]
Accrued compensation and benefits	$ 16,237	$ 22,227
Excise and other tax liabilities	48,803	64,051
Derivative liabilities	34,713	27,622
Accrued interest	33,389	44,418
Product exchange liabilities	24,312	1,693
Deferred gain on sale of general partner interest in TLP	30,113	30,113
Other	43,185	17,001
Total	$ 230,752	$ 207,125