Debt Convertible Senior Notes (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($) d	Dec. 31, 2014 USD ($) $ / shares	Dec. 31, 2013 USD ($)	Dec. 08, 2014 USD ($)
Debt Instrument [Line Items]
Interest expense, Convertible Senior Notes, Amortization		$ 300
Interest Expense, Debt	$ 10,900	600
Proceeds from issuance of Convertible Senior Notes	0	172,500	$ 0
Fair value of outstanding Convertible Senior Notes (2)		190,600
Other Current Assets [Member]
Debt Instrument [Line Items]
Deferred financing costs		300
Other non-current assets [Member]
Debt Instrument [Line Items]
Deferred financing costs		200	$ 500
3.25% Convertible Senior Notes due 2020 [Member] | Convertible Debt [Member]
Debt Instrument [Line Items]
Principal amount of Convertible Senior Notes outstanding	172,500	172,500
Convertible Senior Notes, face amount		$ 172,500		$ 172,500
Convertible Senior Notes, interest rate, stated percentage		3.25%
Debt issuance cost	$ 5,100
Deferred financing costs		$ 4,200
Remaining amortization period of discount on the liability component	5 years	6 years
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs	$ 900
Debt Instrument, Unamortized Discount	$ 25,703	$ 30,403
Convertible Senior Notes, conversion ratio	31.1891
Convertible Senior Notes, conversion price | $ / shares		$ 32.06
Convertible Senior Notes, threshold trading days | d	20
Convertible Senior Notes, threshold consecutive trading days	30 years
Convertible Senior Notes, threshold percentage of stock price trigger	130.00%
Convertible Senior Notes, threshold consecutive business days	5 years
Debt Instrument, Convertible, Threshold Consecutive Trading Days, Following Consecutive Business Days	5 years
Debt Instrument, Convertible, Threshold Percentage of Stock Price Trigger, Following Consecutive Business Days	98.00%
Convertible Senior Notes, observation period	25 years
Carrying value of equity component, net of issuance costs	$ 29,758	$ 29,758		30,700
Interest expense, Convertible Senior Notes, Amortization	5,300
Interest expense, Convertible Senior Notes	5,600	300
Convertible Senior Notes, fair value disclosures				$ 141,900
Proceeds from issuance of Convertible Senior Notes	172,500
Fair value of outstanding Convertible Senior Notes (2)	170,120	190,613
3.25% Convertible Senior Notes due 2020 [Member] | Other Current Assets [Member]
Debt Instrument [Line Items]
Deferred financing costs		600
3.25% Convertible Senior Notes due 2020 [Member] | Other Current Assets [Member] | Convertible Debt [Member]
Debt Instrument [Line Items]
Deferred financing costs	$ 3,500	4,139
3.25% Convertible Senior Notes due 2020 [Member] | Other non-current assets [Member]
Debt Instrument [Line Items]
Deferred financing costs		$ 3,500