Unaudited Condensed Consolidated Statements of Comprehensive (Loss) Income - USD ($)	3 Months Ended				6 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Sep. 30, 2018	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net (loss) income	$ (201,366,000)		$ 354,939,000		$ (193,327,000)	$ 185,650,000
Other comprehensive loss	(46,000)	$ 37,000	(13,000)	$ (11,000)	(9,000)	(24,000)
Comprehensive (loss) income	$ (201,412,000)		$ 354,926,000		$ (193,336,000)	$ 185,626,000