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								12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Basic net income (loss) per share:
Net income (loss)	$ (866,881)	$ 50,735	$ (93,935)	$ (37,517)	$ 48,480	$ (12,388)	$ (18,591)	$ (17,501)	$ (947,597)	$ (52,012)	$ 60,955
Weighted average common shares outstanding									123,387,547	75,513,130	75,590,613
Minimum shares issuable under purchase contracts									13,609,077
Total weighted average common shares outstanding, basic									136,996,624	75,513,130	75,590,613
Basic net income (loss) per share	$ (4.65)	$ 0.35	$ (0.66)	$ (0.50)	$ (0.05)	$ (0.16)	$ (0.25)	$ (0.23)	$ (6.92)	$ (0.69)	$ 0.81
Diluted net income per share:
Net income (loss)	$ (866,881)	$ 50,735	$ (93,935)	$ (37,517)	$ 48,480	$ (12,388)	$ (18,591)	$ (17,501)	$ (947,597)	$ (52,012)	$ 60,955
Number of shares used in basic computation									136,996,624	75,513,130	75,590,613
Total weighted average common shares outstanding, diluted									136,996,624	75,513,130	77,801,096
Diluted net income (loss) per share	$ (4.65)	$ 0.35	$ (0.66)	$ (0.50)	$ (0.05)	$ (0.16)	$ (0.25)	$ (0.23)	$ (6.92)	$ (0.69)	$ 0.78
Time-Vesting Options [Member]
Diluted net income per share:
Weighted average effect of dilutive securities											2,051,346
Restricted Stock Units (RSUs) [Member]
Diluted net income per share:
Weighted average effect of dilutive securities											159,137