Derivative and Hedging Activities - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2019		Jun. 30, 2018	Jun. 30, 2019		Jun. 30, 2018	Mar. 31, 2019	Dec. 31, 2018
Interest Income (Expense), Net	$ 237,690		$ 263,955	$ 479,015		$ 534,253
Derivative Liability								$ 0
Designated as Hedging Instrument [Member]
Derivative, Notional Amount	2,000,000			2,000,000			$ 2,000,000
Interest Income (Expense), Net	207,000			446,000
Designated as Hedging Instrument [Member] | Other Assets [Member]
Derivatives
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member]
Derivative, Notional Amount	2,000,000			2,000,000			2,000,000
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member] | Other Assets [Member]
Derivatives
Loans and leases
Amortized Cost							4,600,000
Cumulative Amount of Fair Value Hedging Adjustments Included in the Carrying Amount of the Hedged Assets	58,354	[1]		58,354	[1]		58,400
Carrying Amount of the Hedged Assets	$ 2,058,354	[1]		$ 2,058,354	[1]		$ 2,000,000

[1] These amounts include the amortized cost basis of closed portfolios used to designated hedging relationships in which the hedged item is the last layer expected to be remaining at the end of the hedging relationship. At June 30, 2019, the amortized cost basis of the closed portfolios used in these hedging relationships was $4.6 billion; the cumulative basis adjustments associated with these hedging relationships was $58.4 million; and the amount of the designated hedged items was $2.0 billion.