Debt - Convertible Notes Hedge Transactions, Conversion and EPS Impact (Details) $ / shares in Units, shares in Thousands, $ in Thousands	1 Months Ended	3 Months Ended			9 Months Ended
	Feb. 28, 2014 USD ($)	Sep. 30, 2015 USD ($) $ / shares shares	Sep. 30, 2014 shares	Dec. 31, 2013 d	Sep. 30, 2015 USD ($) $ / shares shares	Sep. 30, 2014 shares	Mar. 05, 2014 $ / shares	Dec. 16, 2013 $ / shares	Jun. 24, 2013 $ / shares	Nov. 27, 2012 $ / shares
Debt Instrument [Line Items]
Reclassifications of equity to temporary equity, debt conversion					$ 6,900
Dilutive effect of convertible senior notes (in shares) | shares		0	1,043		847	1,118
2017 Convertible Senior Notes [Member]
Debt Instrument [Line Items]
Conversion price (in dollars per share) | $ / shares		$ 31.56			$ 31.56					$ 31.56
Cost of the hedge transaction(s)					$ 50,595
Convertible debt, threshold of stock price trigger				130.00%
Convertible debt, threshold trading days | d				20
Convertible debt, threshold consecutive trading days				30 days
Convertible notes, fair value		$ 144,500			$ 144,500
2020 Convertible Senior Notes [Member]
Debt Instrument [Line Items]
Conversion price (in dollars per share) | $ / shares		$ 45.72			$ 45.72				$ 45.72
Cost of the hedge transaction(s)					$ 18,113
2021 Convertible Senior Notes [Member]
Debt Instrument [Line Items]
Conversion price (in dollars per share) | $ / shares		59.39			$ 59.39		$ 59.39
Cost of the hedge transaction(s)					$ 19,545
Hedging of Convertible Debt Instrument [Member] | 2017 Convertible Senior Notes [Member]
Debt Instrument [Line Items]
Conversion price (in dollars per share) | $ / shares		60.00			$ 60.00			$ 60.00		$ 44.19
Cost of the hedge transaction(s)	$ 27,900
Hedging of Convertible Debt Instrument [Member] | 2020 Convertible Senior Notes [Member]
Debt Instrument [Line Items]
Conversion price (in dollars per share) | $ / shares		61.55			61.55
Hedging of Convertible Debt Instrument [Member] | 2021 Convertible Senior Notes [Member]
Debt Instrument [Line Items]
Conversion price (in dollars per share) | $ / shares		$ 83.14			$ 83.14