Allowance for Loan Losses, Allowance for Losses on Lending-Related Commitments and Impaired Loans (Summary of Impaired Loans by Loan Class) (Detail) - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	$ 42,968	$ 50,748	$ 49,961
Impaired Financing Receivable, Related Allowance	6,611	10,075	6,380
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	53,008	52,609	51,294
Impaired Financing Receivable, Recorded Investment	95,976	103,357	101,255
Impaired Financing Receivable, Unpaid Principal Balance	114,113	122,378	124,249
Impaired Financing Receivable, Average Recorded Investment	97,879	105,874	107,170
Impaired Financing Receivable, Interest Income Recognized	2,860	2,835	6,198
Commercial | Commercial, industrial and other
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	10,253	7,607	9,754
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	12,866	8,046	12,498
Impaired Financing Receivable, Related Allowance	3,280	2,200	2,012
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	10,172	7,788	10,123
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	375	181	792
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	10,092	3,760	8,562
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	10,950	6,731	9,915
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	10,045	4,052	9,885
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized	328	219	521
Commercial | Asset-based lending
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	0	0	0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	0	0	0
Impaired Financing Receivable, Related Allowance	0	0	0
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	0	0	0
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	0	0	0
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	0	0	8
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	0	0	1,570
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	0	0	5
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized	0	0	88
Commercial | Leases
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	387	65	0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	387	65	0
Impaired Financing Receivable, Related Allowance	128	65	0
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	390	66	0
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	10	2	0
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	0	0	0
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	0	0	0
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	0	0	0
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized	0	0	0
Commercial real estate | Construction
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	0	0	0
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	0	0	0
Impaired Financing Receivable, Related Allowance	0	0	0
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	0	0	0
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	0	0	0
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	2,677	2,665	2,328
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	2,677	2,665	2,329
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	2,693	2,650	2,316
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized	77	61	113
Commercial real estate | Land
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	4,538	6,924	4,929
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	4,538	10,539	8,711
Impaired Financing Receivable, Related Allowance	18	50	41
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	4,592	6,931	5,127
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	83	294	547
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	2,979	1,906	888
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	7,492	2,643	2,373
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	3,001	1,924	929
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized	254	50	90
Commercial real estate | Office
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	2,401	7,005	5,050
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	3,059	7,010	6,051
Impaired Financing Receivable, Related Allowance	176	2,414	632
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	2,427	7,060	5,394
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	70	154	314
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	6,967	6,289	3,500
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	8,715	8,780	4,484
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	7,107	6,834	3,613
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized	227	221	237
Commercial real estate | Industrial
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	7,369	1,218	8,413
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	7,773	1,218	9,105
Impaired Financing Receivable, Related Allowance	1,514	558	1,943
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	7,552	1,218	10,590
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	195	34	565
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	3,966	2,022	2,217
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	5,093	2,200	2,426
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	4,326	2,059	2,286
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized	168	88	188
Commercial real estate | Retail
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	7,007	8,336	8,527
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	7,024	9,222	9,230
Impaired Financing Receivable, Related Allowance	264	404	343
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	7,064	8,482	8,596
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	95	194	386
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	1,122	4,099	2,757
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	1,122	5,248	2,925
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	1,129	4,113	2,897
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized	27	112	129
Commercial real estate | Multi-family
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	1,274	2,149	370
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	1,274	2,258	370
Impaired Financing Receivable, Related Allowance	15	322	202
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	1,066	2,168	372
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	18	51	25
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	90	592	2,344
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	174	1,015	2,807
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	119	598	2,390
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized	3	22	117
Commercial real estate | Mixed use and other
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	3,040	10,507	7,590
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	3,162	12,694	7,708
Impaired Financing Receivable, Related Allowance	109	1,847	570
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	3,063	10,557	7,681
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	73	290	328
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	5,435	11,683	10,510
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	5,960	12,008	14,060
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	5,498	12,427	11,939
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized	159	266	624
Home equity
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	1,349	1,673	423
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	1,511	1,728	435
Impaired Financing Receivable, Related Allowance	477	808	333
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	1,443	1,680	351
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	30	34	16
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	7,213	4,236	6,424
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	9,674	5,697	7,987
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	8,356	4,320	5,738
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized	219	118	288
Residential real estate
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	5,230	6,945	4,710
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	5,840	7,138	4,799
Impaired Financing Receivable, Related Allowance	625	1,363	294
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	5,289	6,963	4,618
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	123	137	182
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	12,051	13,258	11,559
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	14,180	14,961	13,979
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	11,997	13,553	11,903
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized	308	294	624
Consumer and other
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivable, with Related Allowance, Recorded Investment	120	180	195
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	148	245	220
Impaired Financing Receivable, Related Allowance	5	44	10
Impaired Financing Receivable, with Related Allowance, Average Recorded Investment	123	190	216
Impaired Financing Receivable, with Related Allowance, Interest Income Recognized	4	6	12
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	416	238	197
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	494	267	267
Impaired Financing Receivable, with No Related Allowance, Average Recorded Investment	427	241	201
Impaired Financing Receivable, with No Related Allowance, Interest Income Recognized	$ 14	$ 7	$ 12