Earnings (Loss) Per Common Share - Additional Information (Details) - USD ($) $ / shares in Units, shares in Thousands	12 Months Ended			51 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017	Oct. 31, 2013
Computation Of Earnings Per Share Line Items
Repurchase of common stock	$ 370,000	$ 1,634,000	$ 1,627,000
Common Stock Repurchase Plan
Computation Of Earnings Per Share Line Items
Shares repurchased	14			296
Repurchase of common stock	$ 400,000			$ 4,200,000
Shares repurchased, average cost per share	$ 26.41			$ 14.05
Maximum
Computation Of Earnings Per Share Line Items
Common stock repurchase program authorized amount					$ 10,000,000