Changes in Accretable Yield for Covered Loans (Detail) - Covered Loans $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Balance at beginning of period	$ 1,037,023
Reclassification to non-accretable difference	(96,788)
Accretion	(137,090)
Balance at end of period	$ 803,145