Stock-Based Compensation Plans and Arrangements - Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Number of Options
Beginning balance (in shares)	4,460,993
Granted (in shares)	0
Exercised (in shares)	(3,051,858)
Canceled (in shares)	(17,316)
Ending balance (in shares)	1,391,819	4,460,993
Exercisable (in shares)	1,391,819
Weighted Average Exercise Price per Share
Beginning balance (in dollars per share)	$ 11.34
Granted (in dollars per share)	0.00
Exercised (in dollars per share)	5.88
Canceled (in dollars per share)	6.19
Ending balance (in dollars per share)	10.44	$ 11.34
Exercisable (in dollars per share)	$ 4.27
Weighted Average Remaining Contractual Term
Weighted Average Remaining Contractual Term, Outstanding, ending balance (in years)	1 year 2 months 14 days
Weighted Average Remaining Contractual Term, Exercisable, ending balance (in years)	1 year 2 months 14 days
Aggregate Intrinsic Value
Aggregate Intrinsic Value, Outstanding, ending balance	$ 5,624
Aggregate Intrinsic Value, Exercisable, ending balance	5,624
Total intrinsic value of options exercised	16,900	$ 16,500	$ 9,300
Cash received from option exercises	400
Tax benefit from exercise of stock options	$ 1,700