Activity in Allowance for Losses on Non-Covered Loans (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Valuation Allowance [Line Items]
Balance, beginning of period				$ 139,857	$ 141,946
Charge-offs				(1,323)	(7,804)
Recoveries				8,349	5,602
Transfer from the allowance for losses on covered loans	[1]			2,416
(Recovery of) provision for non-covered loan losses		$ (9,028)	$ (3,945)	(8,687)	(18,387)
Balance, end of period		146,045	139,744	146,045	139,744
Non-Covered Loans
Valuation Allowance [Line Items]
(Recovery of) provision for non-covered loan losses		(512)		(3,254)
Mortgage Receivable
Valuation Allowance [Line Items]
Balance, beginning of period				122,616	127,840
Charge-offs				(935)	(2,610)
Recoveries				4,197	1,368
Transfer from the allowance for losses on covered loans	[1]			2,250
Balance, end of period		121,568	126,598	121,568	126,598
Mortgage Receivable | Non-Covered Loans
Valuation Allowance [Line Items]
(Recovery of) provision for non-covered loan losses				(6,560)
Other loan
Valuation Allowance [Line Items]
Balance, beginning of period				17,241	14,106
Charge-offs				(388)	(5,194)
Recoveries				4,152	4,234
Transfer from the allowance for losses on covered loans	[1]			166
Balance, end of period		$ 24,477	$ 13,146	24,477	$ 13,146
Other loan | Non-Covered Loans
Valuation Allowance [Line Items]
(Recovery of) provision for non-covered loan losses				$ 3,306

[1] Represents the allowance associated with $14.2 million of loans acquired in the Desert Hills transaction that were transferred from covered loans to non-covered loans upon expiration of the related FDIC loss sharing agreement.