Basis of Financial Statement Presentation - ASC 606 Adjustment Cash Flow (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net income (loss)	$ 35,220	$ 220,439
Depreciation and amortization	13,097	12,459
Change in deferred income taxes	951	(147)
Change in operating assets	(24,520)	24,670
Change in operating liabilities	(49,330)	(39,039)
Other	(488)	(88)
Net cash provided by (used in) operating activities	(15,850)	10,042
Effect of foreign currency fluctuations on cash	$ (7,061)	1,156
As Previously Reported
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net income (loss)		220,606
Depreciation and amortization		12,243
Change in deferred income taxes		(129)
Change in operating assets		24,879
Change in operating liabilities		(39,030)
Other		(60)
Net cash provided by (used in) operating activities		10,257
Effect of foreign currency fluctuations on cash		941
Adjustments | Adjustments
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Net income (loss)		(167)
Depreciation and amortization		216
Change in deferred income taxes		(18)
Change in operating assets		(209)
Change in operating liabilities		(9)
Other		(28)
Net cash provided by (used in) operating activities		(215)
Effect of foreign currency fluctuations on cash		$ 215