Income Taxes - Deferred Tax Assets (Liabilities) (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Losses on loans and other assets	$ 637,955	$ 605,273	$ 645,713
Postretirement and other employee benefits	55,962	34,052	30,023
Incentive and other compensation plans	60,337	36,450	37,772
Interest on loans	57,640	79,147	100,725
Retirement benefits	148,722	120,222
Stock-based compensation	72,090	64,017	63,101
Depreciation and amortization		3,527	1,404
Other	162,086	100,999	121,561
Gross deferred tax assets	1,194,792	1,043,687	1,000,299
Leasing transactions	(285,074)	(280,596)	(284,370)
Unrealized investment gains	(31,121)	(82,065)	(21,779)
Capitalized servicing rights	(59,171)	(46,393)	(46,041)
Interest on subordinated note exchange		(3,125)	(6,075)
Retirement benefits			(9,397)
Depreciation and amortization	(56,731)
Other	(55,611)	(63,814)	(49,450)
Gross deferred tax liabilities	(487,708)	(475,993)	(417,112)
Net deferred tax asset	$ 707,084	$ 567,694	$ 583,187