Significant Accounting Policies - Computation of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Numerator
Numerator for basic and diluted earnings per share - income from continuing operations available to common stockholders	$ 51,259	$ 29,344	$ 8,821	$ 6,979	$ (419)	$ 53,713	$ 15,008	$ 8,285	$ 96,404	$ 76,586	$ 95,400
Denominator
Denominator for basic earnings per share - weighted average shares outstanding (in shares)									50,159	50,350	52,206
Effect of dilutive securities - stock options and other stock units (in shares)									219	247	467
Denominator for diluted earnings per share - adjusted weighted average shares outstanding (in shares)									50,378	50,597	52,673
Earnings per share:
Basic (in dollars per share)	$ 1.02	$ 0.58	$ 0.18	$ 0.14	$ (0.01)	$ 1.07	$ 0.30	$ 0.16	$ 1.92	$ 1.52	$ 1.83
Diluted (in dollars per share)	$ 1.02	$ 0.58	$ 0.18	$ 0.14	$ (0.01)	$ 1.07	$ 0.30	$ 0.16	$ 1.91	$ 1.51	$ 1.81