Off-Balance Sheet Arrangements, Guarantees and Other Commitments - Summary of Commercial and Standby Letters of Credit (Additional Information) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Venture capital and private equity fund investments
Commitments and Contingencies Disclosure [Line Items]
Commitments to invest, period from the inception of the fund	10 years
Call unrestricted, percentage of committed capital	100.00%
Venture capital and private equity fund investments | Lower Limit
Commitments and Contingencies Disclosure [Line Items]
Expected commitment period to invest in venture capital and private equity funds (in years)	5 years
Venture capital and private equity fund investments | Upper Limit
Commitments and Contingencies Disclosure [Line Items]
Expected commitment period to invest in venture capital and private equity funds (in years)	7 years
Standby Letter of Credit
Commitments and Contingencies Disclosure [Line Items]
Deferred fees	$ 10	$ 10
Collateral in the form of cash	$ 785