Segment Results (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013		Dec. 31, 2013
Segment Reporting Information [Line Items]
Net interest income	$ 283,492		$ 299,884		$ 567,642		$ 575,060
(Recovery of) provision for loan losses	188		9,618		(14,442)		19,120
Non-Interest Income	52,593		53,745		89,828		129,296
Non-interest expense	147,836	[1]	151,665	[1]	294,161	[1]	307,761	[1]
Income before income taxes	188,061		192,346		377,751		377,475
Income tax expense	69,373		69,829		143,809		136,283
Net income	118,688		122,517		233,942		241,192
Identifiable segment assets (period-end)	48,604,772		44,185,838		48,604,772		44,185,838		46,688,287
Third Party
Segment Reporting Information [Line Items]
Non-Interest Income	52,593	[2]	53,745	[2]	89,828	[2]	129,296	[2]
Banking Operations
Segment Reporting Information [Line Items]
Net interest income	280,008		293,678		561,255		561,741
(Recovery of) provision for loan losses	188		9,618		(14,442)		19,120
Non-Interest Income	32,807		25,777		50,912		70,340
Non-interest expense	133,929	[1]	131,201	[1]	264,754	[1]	266,127	[1]
Income before income taxes	178,698		178,636		361,855		346,834
Income tax expense	65,879		64,633		137,888		124,667
Net income	112,819		114,003		223,967		222,167
Identifiable segment assets (period-end)	47,931,214		43,127,156		47,931,214		43,127,156
Banking Operations | Third Party
Segment Reporting Information [Line Items]
Non-Interest Income	36,578	[2]	29,835	[2]	58,462	[2]	78,557	[2]
Banking Operations | Inter-segment
Segment Reporting Information [Line Items]
Non-Interest Income	(3,771)		(4,058)		(7,550)		(8,217)
Residential Mortgage Banking
Segment Reporting Information [Line Items]
Net interest income	3,484		6,206		6,387		13,319
(Recovery of) provision for loan losses	0		0		0		0
Non-Interest Income	19,786		27,968		38,916		58,956
Non-interest expense	13,907	[1]	20,464	[1]	29,407	[1]	41,634	[1]
Income before income taxes	9,363		13,710		15,896		30,641
Income tax expense	3,494		5,196		5,921		11,616
Net income	5,869		8,514		9,975		19,025
Identifiable segment assets (period-end)	673,558		1,058,682		673,558		1,058,682
Residential Mortgage Banking | Third Party
Segment Reporting Information [Line Items]
Non-Interest Income	16,015	[2]	23,910	[2]	31,366	[2]	50,739	[2]
Residential Mortgage Banking | Inter-segment
Segment Reporting Information [Line Items]
Non-Interest Income	$ 3,771		$ 4,058		$ 7,550		$ 8,217

[1] Includes both direct and indirect expenses.

[2] Includes ancillary fee income.