Debt - Interest Related to Convertible Debt (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Aug. 31, 2015
Schedule of Convertible Debt [Line Items]
Amortization of debt discount	$ 604	$ 1,092	$ 1,215
Effective percentage rate	6.21%	6.21%	6.21%
4.50% Senior Exchangeable Notes
Schedule of Convertible Debt [Line Items]
Contractual interest coupon	$ 3,438	$ 5,930	$ 7,271
Amortization of debt discount	$ 1,267	$ 1,957	$ 2,281
Fixed interest rate	4.50%	4.50%	4.50%	4.50%
Convertible Debt
Schedule of Convertible Debt [Line Items]
Total interest expense recognized	$ 4,705	$ 7,887	$ 9,552