Senior Convertible Notes - Schedule of Activity and Balances Associated with the Notes and Related Deferred Transaction Costs (Details) - USD ($) $ in Thousands		2 Months Ended	3 Months Ended
	Mar. 18, 2016	Dec. 31, 2014	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015
Convertible Notes And Deferred Transaction Costs[Roll forward]
Transactions Costs, beginning of period			$ 7,769
Less: amortization			(4,153)				$ (617)
Conversions			(82,274)				0
Transactions Costs, end of period			3,617	$ 7,769
Convertible Senior Notes Due 2019
Convertible Notes And Deferred Transaction Costs[Roll forward]
Notes Balance, beginning of period		$ 200,000	159,011	159,011	$ 177,787	$ 200,000	200,000
Transactions Costs, beginning of period		12,747	7,770	8,276	9,820	11,719	12,336
Notes, net of Transaction Costs, beginning of period		187,253	151,241	150,735	167,967	188,281	187,664
Less: amortization	$ (3,600)	(411)	(4,153)	(506)	(1,544)	(1,899)	(617)
Conversions	$ (79,800)		(79,829)		(18,776)	(22,213)
Notes Balance, end of period		200,000	79,182	159,011	159,011	177,787	200,000
Notes, net of Transaction Costs, end of period		187,664	75,565	151,241	150,735	167,967	188,281
Transactions Costs, end of period		$ 12,336	$ 3,617	$ 7,770	$ 8,276	$ 9,820	$ 11,719