Earnings per Share - Schedule Of Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share [Abstract]
Net income attributable to continuing operations	$ 25,216	$ 25,486	$ 29,306	$ 12,683	$ 20,840	$ 15,712	$ 23,722	$ 9,316	$ 92,691	$ 69,590	$ 87,447
Preferred stock dividends									42	41	41
Income from continuing operations available to common equity									92,649	69,549	87,406
Dividends and undistributed earnings allocated to participating securities									(144)	(192)	(546)
Income from continuing operations available to common shareholders									92,505	69,357	86,860
Net income attributable to discontinued operations	$ (300)	$ (1,300)	$ 1,777	$ (932)	$ 11	$ 264	$ 576	$ 366	(755)	1,217	1,059
Preferred stock dividends									0	(1)	(1)
Income from discontinued operations available to common equity									(755)	1,216	1,058
Dividends and undistributed earnings allocated to participating securities									1	(3)	(7)
Income from discontinued operations available to common shareholders									$ (754)	$ 1,213	$ 1,051
Basic weighted-average shares outstanding (in shares)									37,456	37,293	37,138
Stock options and other stock compensation (in shares)									530	417	590
Diluted weighted-average shares outstanding (in shares)									37,986	37,710	37,728
Antidilutive stock options (in shares)									0	658	0
Earnings per share attributable to continuing operations:
Earnings per share attributable to continuing operations, basic (dollars per share)	$ 0.67	$ 0.68	$ 0.78	$ 0.34	$ 0.56	$ 0.42	$ 0.63	$ 0.25	$ 2.47	$ 1.86	$ 2.34
Earnings per share attributable to continuing operations, diluted (dollars per share)	0.66	0.67	0.77	0.34	0.55	0.41	0.62	0.25	2.44	1.84	2.30
Earnings per share attributable to discontinued operations:
Earnings per share attributable to discontinued operations, basic (dollars per share)	(0.01)	(0.04)	0.05	(0.03)	0.00	0.01	0.02	0.01	(0.02)	0.03	0.03
Earnings per share attributable to discontinued operations, diluted (dollars per share)	$ (0.01)	$ (0.04)	$ 0.05	$ (0.03)	$ 0.00	$ 0.01	$ 0.01	$ 0.01	$ (0.02)	$ 0.03	$ 0.03