Supplemental Consolidated Financial Information (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Quarterly Financial Information [Line Items]
Interest income	$ 147,802	$ 143,324	$ 140,161	$ 134,101	$ 118,709	$ 116,758	$ 116,245	$ 110,019	$ 565,388		$ 461,731		$ 431,226
Interest expense	(7,732)	(7,869)	(9,708)	(13,802)	(14,191)	(10,417)	(9,809)	(9,179)	(39,111)		(43,596)		(49,076)
Net interest income	140,070	135,455	130,453	120,299	104,518	106,341	106,436	100,840	526,277		418,135		382,150
Reduction of (provision for) loan losses	(8,245)	(769)	(134)	3,047	(15,504)	(10,971)	(7,408)	(10,745)
Noninterest income	73,059	95,611	123,708	89,954	71,864	86,236	40,157	49,273	382,332		247,530		97,743
Noninterest expense	(134,710)	(127,451)	(121,032)	(117,435)	(115,891)	(104,171)	(104,180)	(98,576)	(500,628)	[1]	(422,818)	[1]	(343,866)
Income (loss) before income tax expense	70,174	102,846	132,995	95,865	44,987	77,435	35,005	40,792	401,880	[2]	198,219	[2]	45,847	[2]
Income tax expense	26,284	26,770	43,263	22,770	11,005	24,996	13,819	11,582	119,087		61,402		35,207
Net income before noncontrolling interests	43,890	76,076	89,732	73,095	33,982	52,439	21,186	29,210	282,793		136,817		10,640
Net income attributable to noncontrolling interests	(8,316)	(38,505)	(23,982)	(40,088)	(16,495)	(14,652)	(66)	(10,653)	(110,891)		(41,866)		37,370
Net income available to common stockholders	$ 35,574	$ 37,571	$ 65,750	$ 33,007	$ 17,487	$ 37,787	$ 21,120	$ 18,557	$ 171,902		$ 94,951		$ 22,674
Earnings per common share-basic	$ 0.82	$ 0.87	$ 1.53	$ 0.78	$ 0.42	$ 0.90	$ 0.51	$ 0.45	$ 4.00		$ 2.27		$ 0.67
Earnings per common share-diluted	$ 0.81	$ 0.86	$ 1.50	$ 0.76	$ 0.41	$ 0.89	$ 0.50	$ 0.44	$ 3.94		$ 2.24		$ 0.66

[1] The Global Commercial Bank segment includes direct depreciation and amortization of $12.2 million, $9.7 million and $9.9 million in 2011, 2010 and 2009, respectively.

[2] The internal reporting model used by management to assess segment performance does not calculate tax expense by segment. Our effective tax rate is a reasonable approximation of the segment rates.