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, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings Per Share [Abstract]
Net income attributable to continuing operations	$ 20,840	$ 15,712	$ 23,722	$ 9,316	$ 33,119	$ 18,674	$ 22,132	$ 13,522	$ 69,590	$ 87,447	$ 85,858
Preferred Stock Dividends and Other Adjustments									41	41	41
Income from continuing operations available to common equity									69,549	87,406	85,817
Dividends and undistributed earnings allocated to participating securities									(192)	(546)	(643)
Income from continuing operations available to common shareholders									69,357	86,860	85,174
Net income attributable to discontinued operations	$ 11	$ 264	$ 576	$ 366	$ (432)	$ 631	$ 356	$ 504	1,217	1,059	2,389
Preferred stock dividends									(1)	(1)	(1)
Income from discontinued operations available to common equity									1,216	1,058	2,388
Dividends and undistributed earnings allocated to participating securities									(3)	(7)	(18)
Income from discontinued operations available to common shareholders									$ 1,213	$ 1,051	$ 2,370
Basic weighted-average shares outstanding (in shares)									37,293	37,138	36,868
Stock options and other stock compensation (in shares)									417	590	582
Diluted weighted-average shares outstanding (in shares)									37,710	37,728	37,450
Antidilutive stock options (in shares)									658	0	15
Earnings per share attributable to continuing operations:
Earnings per share attributable to continuing operations, basic (dollars per share)	$ 0.56	$ 0.42	$ 0.63	$ 0.25	$ 0.88	$ 0.50	$ 0.59	$ 0.37	$ 1.86	$ 2.34	$ 2.31
Earnings per share attributable to continuing operations, diluted (dollars per share)	0.55	0.41	0.62	0.25	0.87	0.49	0.58	0.36	1.84	2.30	2.28
Earnings per share attributable to discontinued operations:
Earnings per share attributable to discontinued operations, basic (dollars per share)	0.00	0.01	0.02	0.01	(0.01)	0.02	0.01	0.01	0.03	0.03	0.06
Earnings per share attributable to discontinued operations, diluted (dollars per share)	$ 0.00	$ 0.01	$ 0.01	$ 0.01	$ (0.01)	$ 0.02	$ 0.01	$ 0.01	$ 0.03	$ 0.03	$ 0.06