Business Combination (Acquired Identifiable Assets and Liabilities Assumed) (Detail) - MB Financial, Inc. - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 22, 2019
Consideration paid
Cash payments	$ 469
Fair value of common stock issued	3,121
Stock-based awards	38
Dividend receivable from MB Financial, Inc.	(20)
Total consideration paid	$ 3,608
Fair value of noncontrolling interest in acquiree		$ 197
Assets
Cash and due from banks		1,679
Federal funds sold		35
Other short-term investments		53
Available-for-sale debt and other securities		832
Held-to-maturity securities		4
Equity securities		51
Loans and leases held for sale		12
Portfolio loans and leases		13,490
Bank premises and equipment		254
Operating lease equipment		403
Intangible assets		183
Servicing rights		263
Other assets		697
Total assets acquired		17,956
Liabilities
Deposits		14,489
Other short-term borrowings		348
Accrued taxes, interest and expenses		264
Other liabilities		180
Long-term debt		713
Total liabilities assumed		15,994
Net identifiable assets acquired		1,962
Goodwill		$ 1,843