Debt - Convertible Notes Hedge Transactions (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	Feb. 28, 2014	Dec. 31, 2015	Mar. 05, 2014	Dec. 16, 2013	Jun. 24, 2013	Nov. 27, 2012
2017 Convertible Senior Notes [Member]
Debt Instrument [Line Items]
Cost of the hedge transaction(s)		$ 50,595
Conversion price (in dollars per share)		$ 31.56				$ 31.56
2020 Convertible Senior Notes [Member]
Debt Instrument [Line Items]
Cost of the hedge transaction(s)		$ 18,113
Conversion price (in dollars per share)		$ 45.72			$ 45.72
2021 Convertible Senior Notes [Member]
Debt Instrument [Line Items]
Cost of the hedge transaction(s)		$ 19,545
Conversion price (in dollars per share)		$ 59.39	$ 59.39
Hedging of Convertible Debt Instrument [Member] | 2017 Convertible Senior Notes [Member]
Debt Instrument [Line Items]
Cost of the hedge transaction(s)	$ 27,900
Conversion price (in dollars per share)		60.00		$ 60.00		$ 44.19
Hedging of Convertible Debt Instrument [Member] | 2020 Convertible Senior Notes [Member]
Debt Instrument [Line Items]
Conversion price (in dollars per share)		61.55
Hedging of Convertible Debt Instrument [Member] | 2021 Convertible Senior Notes [Member]
Debt Instrument [Line Items]
Conversion price (in dollars per share)		$ 83.14