Net Income (Loss) Per Share (Computation of Basic Net Income (Loss) Per Share of Common Stock) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Sep. 30, 2018	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Net Income (Loss) Per Share [Abstract]
Net income (loss)	$ (93,935)	$ (37,517)	$ (18,591)	$ (17,501)	$ (131,451)	$ (36,092)
Weighted average common shares outstanding	123,794,511		75,506,552		99,897,191	75,555,700
Minimum shares issuable under purchase contracts	18,429,325				9,214,662
Weighted average common shares outstanding	142,223,836		75,506,552		109,111,853	75,555,700
Basic net income (loss) per share	$ (0.66)		$ (0.25)		$ (1.20)	$ (0.48)