Business Segments - Schedule of Financial Data for Business Segments (Detail) (USD $) In Thousands, 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
Segment Reporting Information [Line Items]
Average interest earning assets	$ 14,242,202				$ 14,109,728				$ 14,242,202	$ 14,109,728	$ 12,814,436
Interest income	156,915	153,779	152,370	153,033	162,969	167,230	166,858	174,136	616,097	671,193	673,824
Interest expense	40,787	42,110	42,483	42,997	44,440	45,408	44,787	46,677	168,377	181,312	199,013
Net interest income (loss)	116,128	111,669	109,887	110,036	118,529	121,822	122,071	127,459	447,720	489,881	474,811
Provision for credit losses	6,440	5,334	2,552	1,769	5,200	7,250	7,405	5,697	16,095	25,552	53,335
Net interest income (loss) after provision for credit losses									431,625	464,329	421,476
Non-interest income									128,653	120,946	112,297
Non-interest expense	96,092	94,461	95,346	95,439	95,623	93,219	91,510	94,548	381,338	374,900	338,556
Internal expense transfer
Income (loss) before income taxes	55,669	34,264	44,883	44,124	51,531	61,849	47,186	49,809	178,940	210,375	195,217
Return on average interest earning assets (pre-tax)	1.26%				1.49%				1.26%	1.49%	1.52%
Consumer Lending [Member]
Segment Reporting Information [Line Items]
Average interest earning assets	3,915,395				3,941,374				3,915,395	3,941,374	3,394,161
Interest income									157,482	174,978	171,939
Interest expense									41,556	45,499	47,832
Net interest income (loss)									115,926	129,479	124,107
Provision for credit losses									2,094	4,969	6,806
Net interest income (loss) after provision for credit losses									113,832	124,510	117,301
Non-interest income									75,028	83,765	45,830
Non-interest expense									77,231	69,281	56,884
Internal expense transfer									64,142	65,561	55,059
Income (loss) before income taxes									47,487	73,433	51,188
Return on average interest earning assets (pre-tax)	1.21%				1.86%				1.21%	1.86%	1.51%
Commercial Lending [Member]
Segment Reporting Information [Line Items]
Average interest earning assets	7,272,573				7,296,895				7,272,573	7,296,895	6,214,319
Interest income									380,369	407,288	375,873
Interest expense									77,187	84,234	87,574
Net interest income (loss)									303,182	323,054	288,299
Provision for credit losses									14,001	20,583	46,529
Net interest income (loss) after provision for credit losses									289,181	302,471	241,770
Non-interest income									(7,219)	(1,701)	16,965
Non-interest expense									57,096	54,963	48,829
Internal expense transfer									118,546	120,993	99,851
Income (loss) before income taxes									106,320	124,814	110,055
Return on average interest earning assets (pre-tax)	1.46%				1.71%				1.46%	1.71%	1.77%
Investment Management [Member]
Segment Reporting Information [Line Items]
Average interest earning assets	3,054,234				2,871,459				3,054,234	2,871,459	3,205,756
Interest income									86,564	96,582	132,530
Interest expense									32,416	33,148	45,176
Net interest income (loss)									54,148	63,434	87,354
Provision for credit losses
Net interest income (loss) after provision for credit losses									54,148	63,434	87,354
Non-interest income									5,962	6,817	7,381
Non-interest expense									1,355	1,219	1,016
Internal expense transfer									50,011	47,749	51,644
Income (loss) before income taxes									8,744	21,283	42,075
Return on average interest earning assets (pre-tax)	0.29%				0.74%				0.29%	0.74%	1.31%
Corporate and Other Adjustments [Member]
Segment Reporting Information [Line Items]
Average interest earning assets
Interest income									(8,318)	(7,655)	(6,518)
Interest expense									17,218	18,431	18,431
Net interest income (loss)									(25,536)	(26,086)	(24,949)
Provision for credit losses
Net interest income (loss) after provision for credit losses									(25,536)	(26,086)	(24,949)
Non-interest income									54,882	32,065	42,121
Non-interest expense									245,656	249,437	231,827
Internal expense transfer									(232,699)	(234,303)	(206,554)
Income (loss) before income taxes									$ 16,389	$ (9,155)	$ (8,101)