Summary of Significant Accounting Policies (Details) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2015
Class of Stock [Line Items]
Authorized amount from Board of Directors for share repurchase			$ 250,000,000
Number of shares repurchased (in shares)	0	2,070,600
Cost of shares repurchased		$ 34,700,000
Remaining authorization under the program	$ 215,400,000