Income Taxes - Deferred Tax Assets (Liabilities) (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Losses on loans and other assets	$ 590,288	$ 637,955	$ 605,273
Retirement benefits	143,067	148,722	120,222
Postretirement and other employee benefits	52,512	55,962	34,052
Incentive and other compensation plans	36,616	60,337	36,450
Interest on loans	61,266	57,640	79,147
Stock-based compensation	52,181	72,090	64,017
Unrealized investment losses	10,741
Depreciation and amortization			3,527
Other	106,876	162,086	100,999
Gross deferred tax assets	1,053,547	1,194,792	1,043,687
Leasing transactions	(266,268)	(285,074)	(280,596)
Unrealized investment gains		(31,121)	(82,065)
Capitalized servicing rights	(71,108)	(59,171)	(46,393)
Depreciation and amortization	(63,959)	(56,731)
Other	(87,200)	(55,611)	(66,939)
Gross deferred tax liabilities	(488,535)	(487,708)	(475,993)
Net deferred tax asset	$ 565,012	$ 707,084	$ 567,694