Past Due Loans, Allowance For Credit Losses, Impaired Loans, and TDRs (Detail) - Allowance for Credit Losses - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	$ 74,510	$ 87,121	$ 102,812
Charge-offs	(26,917)	(40,184)	(38,580)
Recoveries	6,701	8,205	8,382
Net charge-offs	(20,216)	(31,979)	(30,198)
Provision for loan and covered loan losses and other	20,561	19,368	14,507
Ending Balance	74,855	74,510	87,121
Commercial, Industrial, and Agricultural
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	29,458	30,381	36,761
Charge-offs	(15,885)	(17,424)	(12,094)
Recoveries	2,573	3,800	3,797
Net charge-offs	(13,312)	(13,624)	(8,297)
Provision for loan and covered loan losses and other	20,928	12,701	1,917
Ending Balance	37,074	29,458	30,381
Office, Retail, and Industrial
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	10,992	10,405	11,432
Charge-offs	(2,887)	(7,345)	(4,744)
Recoveries	467	497	228
Net charge-offs	(2,420)	(6,848)	(4,516)
Provision for loan and covered loan losses and other	4,544	7,435	3,489
Ending Balance	13,116	10,992	10,405
Multi-family
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	2,249	2,017	3,575
Charge-offs	(545)	(943)	(1,029)
Recoveries	15	87	584
Net charge-offs	(530)	(856)	(445)
Provision for loan and covered loan losses and other	743	1,088	(1,113)
Ending Balance	2,462	2,249	2,017
Construction
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	2,297	6,316	9,223
Charge-offs	(136)	(1,052)	(1,916)
Recoveries	350	166	1,032
Net charge-offs	214	(886)	(884)
Provision for loan and covered loan losses and other	(1,071)	(3,133)	(2,023)
Ending Balance	1,440	2,297	6,316
Other Commercial Real Estate
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	8,327	10,817	13,531
Charge-offs	(2,643)	(4,834)	(4,784)
Recoveries	1,993	1,727	1,646
Net charge-offs	(650)	(3,107)	(3,138)
Provision for loan and covered loan losses and other	(1,589)	617	424
Ending Balance	6,088	8,327	10,817
Consumer
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	12,145	13,010	12,862
Charge-offs	(4,187)	(7,574)	(9,414)
Recoveries	1,183	729	1,071
Net charge-offs	(3,004)	(6,845)	(8,343)
Provision for loan and covered loan losses and other	2,671	5,980	8,491
Ending Balance	11,812	12,145	13,010
Covered Loans
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	7,226	12,559	12,062
Charge-offs	(634)	(1,012)	(4,599)
Recoveries	120	1,199	24
Net charge-offs	(514)	187	(4,575)
Provision for loan and covered loan losses and other	(5,074)	(5,520)	5,072
Ending Balance	1,638	7,226	12,559
Reserve for Unfunded Commitments
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	1,816	1,616	3,366
Charge-offs	0	0	0
Recoveries	0	0	0
Net charge-offs	0	0	0
Provision for loan and covered loan losses and other	(591)	200	(1,750)
Ending Balance	$ 1,225	$ 1,816	$ 1,616