Schedule Of Earnings Per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Earnings Per Share [Abstract]
Net income attributable to continuing operations	$ 24,929		$ 18,987		$ 23,315		$ 18,627		$ 19,216		$ 18,173		$ 27,078		$ 23,090		$ 85,858		$ 87,557		$ 67,518
Preferred stock dividends																	(41)		(41)		(41)
Income from continuing operations available to common equity																	85,817		87,516		67,477
Dividends and undistributed earnings allocated to participating securities																	(643)		(836)		(730)
Income from continuing operations available to common shareholders																	85,174		86,680		66,747
Net income attributable to discontinued operations	482		514		734		659		271		1,060		917		832		2,389		3,080		2,334
Preferred stock dividends																	(1)		(1)		(1)
Income from discontinued operations available to common equity																	2,388		3,079		2,333
Dividends and undistributed earnings allocated to participating securities																	(18)		(29)		(25)
Income from discontinued operations available to common shareholders																	$ 2,370		$ 3,050		$ 2,308
Basic weighted-average shares outstanding																	36,868		36,564		36,221
Stock options and other stock compensation																	582		478		610
Diluted weighted-average shares outstanding																	37,450		37,042		36,831
Antidilutive stock options																	15		744		894
Earnings per share attributable to continuing operations:
Income from continuing operations, Basic (dollars per share)	$ 0.67	[1]	$ 0.51	[1]	$ 0.63	[1]	$ 0.50	[1]	$ 0.52	[1]	$ 0.49	[1]	$ 0.74	[1]	$ 0.63	[1]	$ 2.31	[1]	$ 2.37	[1]	$ 1.85
Income from continuing operations, Diluted (dollars per share)	$ 0.66	[1]	$ 0.51	[1]	$ 0.62	[1]	$ 0.49	[1]	$ 0.51	[1]	$ 0.48	[1]	$ 0.73	[1]	$ 0.62	[1]	$ 2.28	[1]	$ 2.34	[1]	$ 1.81
Earnings per share attributable to discontinued operations:
Income from discontinued operations, Basic (dollars per share)	$ 0.01	[1]	$ 0.01	[1]	$ 0.02	[1]	$ 0.02	[1]	$ 0.01	[1]	$ 0.03	[1]	$ 0.02	[1]	$ 0.02	[1]	$ 0.06	[1]	$ 0.08	[1]	$ 0.06
Income from discontinued operations, Diluted (dollars per share)	$ 0.01	[1]	$ 0.01	[1]	$ 0.02	[1]	$ 0.02	[1]	$ 0.01	[1]	$ 0.03	[1]	$ 0.02	[1]	$ 0.02	[1]	$ 0.06	[1]	$ 0.08	[1]	$ 0.06

[1] Per share amounts are calculated independently for each period presented; therefore, the sum of the quarterly per share amounts may not equal the per share amounts for the year.