Earnings Per Share - Additional Information (Details) - USD ($) $ in Thousands		1 Months Ended	12 Months Ended
	Jun. 16, 2017	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Nov. 30, 2016
Earnings Per Share Disclosure [Line Items]
Preferred stock, shares authorized (in shares)			15,000,000
Payment for repurchase of common stock			$ 250,000	$ 0	$ 0
Shares available for repurchase (in shares)			12,658,917
Preferred shares issued			0
Accelerated Share Repurchase Agreement
Earnings Per Share Disclosure [Line Items]
Payment for repurchase of common stock		$ 250,000
Maximum
Earnings Per Share Disclosure [Line Items]
Number of shares authorized to be repurchased (in shares)						15,000,000
Restricted Stock
Earnings Per Share Disclosure [Line Items]
Number of shares containing nonforfeitable rights to dividends (in shares)			8,050
Initial Delivery | Accelerated Share Repurchase Agreement
Earnings Per Share Disclosure [Line Items]
Repurchase of common stock shares (in shares)		1,948,178
Final Settlement | Accelerated Share Repurchase Agreement
Earnings Per Share Disclosure [Line Items]
Repurchase of common stock shares (in shares)	392,905
Total Delivery | Accelerated Share Repurchase Agreement
Earnings Per Share Disclosure [Line Items]
Repurchase of common stock shares (in shares)			2,341,083
Common Stock
Earnings Per Share Disclosure [Line Items]
Common stock repurchased				0	0