Reconciliation of Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Earnings Per Share [Abstract]
Net income from continuing operations for basic and diluted earnings per share	$ 29,217	$ 17,154	$ 53,111	$ 28,223
Net income from discontinued operations for basic and diluted earnings per share		4,897		9,995
Net income	$ 29,217	$ 22,051	$ 53,111	$ 38,218
Weighted average shares outstanding - basic	33,552	33,389	33,560	33,382
Dilutive effect of stock options and restricted stock	163	173	90	138
Weighted average shares outstanding - diluted	33,715	33,562	33,650	33,520
Earnings per share from continuing operations
Basic	$ 0.87	$ 0.51	$ 1.58	$ 0.84
Diluted	0.87	0.51	1.58	0.84
Earnings per share from discontinued operations
Basic		0.15		0.30
Diluted		0.15		0.30
Earnings per share net income
Basic	0.87	0.66	1.58	1.14
Diluted	$ 0.87	$ 0.66	$ 1.58	$ 1.14