Long-term Debt - Schedule of Outstanding Convertible Note Balances (Details) - Senior Notes - USD ($)	Sep. 30, 2016	Dec. 31, 2015	Jun. 30, 2014
Debt Instrument [Line Items]
Principal	$ 200,000,000	$ 200,000,000	$ 200,000,000.0
Less: debt discount and unamortized debt issuance costs	(28,812,000)	(35,562,000)
Net carrying amount	171,188,000	164,438,000
Equity component	$ 40,896,000	$ 40,896,000