Short-Term Borrowings - Schedule of Remaining Contractual Maturity of Secured Borrowings and Class of Collateral Pledged Under Repurchase Agreements (Detail) $ in Thousands	Mar. 31, 2016 USD ($)
Assets Sold under Agreements to Repurchase [Line Items]
Secured borrowings and class of collateral pledged under repurchase agreements	$ 329,060
U.S. Treasury [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Secured borrowings and class of collateral pledged under repurchase agreements	329,060
Overnight and Continuous [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Secured borrowings and class of collateral pledged under repurchase agreements	329,060
Overnight and Continuous [Member] | U.S. Treasury [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Secured borrowings and class of collateral pledged under repurchase agreements	$ 329,060