Stock-Based Compensation - Summary of the Activity in the Stock Option Plan (Detail) $ / shares in Units, shares in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) $ / shares shares
Stock Based Compensation [Abstract]
Outstanding, Shares, Beginning Balance | shares	694
Exercised, Shares | shares	(193)
Forfeited/expired, Shares | shares	(276)
Outstanding, Shares, Ending Balance | shares	225
Options exercisable at end of year, Shares | shares	225
Weighted Average Exercise Price, Beginning of Period | $ / shares	$ 15.27
Exercised, Weighted Average Exercise Price | $ / shares	14.01
Forfeited/expired, Weighted Average Exercise Price | $ / shares	18.89
Weighted Average Exercise Price, End of Period | $ / shares	11.92
Options exercisable at end of year, Weighted Average Exercise Price | $ / shares	$ 11.92
Weighted Average Remaining Contractual Term in Years, End of Period	1 year 7 months 28 days
Options exercisable at end of year, Weighted Average Remaining Contractual Terms in Years	1 year 7 months 28 days
Aggregate Intrinsic Value, End of Period | $	$ 1,436,000
Options exercisable at end of year, Aggregate Intrinsic Value | $	$ 1,436,000