Cumulative basis adjustment for fair value hedges (Detail) - Loans and leases - USD ($) $ in Thousands	Jun. 30, 2019	[1]	Mar. 31, 2019
Carrying Amount of the Hedged Assets	$ 2,058,354		$ 2,000,000
Cumulative Amount of Fair Value Hedging Adjustments Included in the Carrying Amount of the Hedged Assets	$ 58,354		$ 58,400

[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.