Long Term Debt (Details) - USD ($)		12 Months Ended
	Nov. 02, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Net proceeds		$ 222,498,000	$ 0	$ 0
Convertible senior notes due 2023
Debt Instrument [Line Items]
Proceeds from issuance of debt	$ 230,000,000
Interest rate (as a percent)	3.25%
Net proceeds	$ 222,500,000
Transaction costs	$ 7,500,000
Frequency of periodic payment	2
Conversion rate, in shares		29.0276
Principal amount for conversion rate		$ 1,000
Conversion price (in dollars per share)		$ 34.45
Redemption price to principal amount, in percent		100.00%
Notes fair value		$ 266,200,000