Summary of Significant Accounting Policies (Details) - USD ($)		12 Months Ended
	May 05, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	May 31, 2015	Apr. 30, 2015
Class of Stock [Line Items]
Stock split, reclassification from APIC to Common Stock				$ 0
Authorized amount from Board of Directors for share repurchase			$ 250,000,000
Cost of shares repurchased		$ 34,700,000	$ 115,000,000	31,500,000
Number of shares repurchased (in shares)		2,070,600	3,947,320
Common stock, shares authorized		400,000,000	400,000,000		400,000,000	200,000,000
Common stock, par value (in dollars per share)		$ 0.01			$ 0.01	$ 1.00
Common Stock
Class of Stock [Line Items]
Stock split, conversion ratio	2
Stock dividend	100.00%
Stock split, reclassification from APIC to Common Stock				$ 78,000,000