Activity in Allowance for Losses for Non-Covered Loans and Covered Loans (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Individually evaluated for impairment	$ 0	$ 0
Allowance for Loan Losses, Collectively evaluated for impairment	151,328	145,196
Allowance for Loan Losses	179,708	178,519
Acquired loans with deteriorated credit quality
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, other	28,380	33,323
Mortgage Receivable
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Individually evaluated for impairment	0	0
Allowance for Loan Losses, Collectively evaluated for impairment	127,127	122,712
Allowance for Loan Losses	140,427	137,295
Mortgage Receivable | Acquired loans with deteriorated credit quality
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, other	13,300	14,583
Other loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, Individually evaluated for impairment	0	0
Allowance for Loan Losses, Collectively evaluated for impairment	24,201	22,484
Allowance for Loan Losses	39,281	41,224
Other loans | Acquired loans with deteriorated credit quality
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for Loan Losses, other	$ 15,080	$ 18,740