Allowance for Loan and Lease Losses (Credit Quality Information) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Credit Quality Information
Recorded investment	$ 6,737,816	$ 6,303,516
Originated
Credit Quality Information
Recorded investment	6,449,687	5,909,109
Acquired
Credit Quality Information
Recorded investment	288,129	394,407
Commercial real estate
Credit Quality Information
Recorded investment	2,491,011	2,330,725
Commercial real estate | Originated
Credit Quality Information
Recorded investment	2,400,037	2,208,904
Commercial real estate | Acquired
Credit Quality Information
Recorded investment	90,974	121,821
Commercial real estate | Pass | Originated
Credit Quality Information
Recorded investment	2,379,925	2,198,377
Commercial real estate | Pass | Acquired
Credit Quality Information
Recorded investment	81,360	111,919
Commercial real estate | OAEM | Originated
Credit Quality Information
Recorded investment	17,006	6,096
Commercial real estate | OAEM | Acquired
Credit Quality Information
Recorded investment	597	626
Commercial real estate | Substandard | Originated
Credit Quality Information
Recorded investment	3,106	4,431
Commercial real estate | Substandard | Acquired
Credit Quality Information
Recorded investment	9,017	9,276
Commercial real estate | Doubtful | Originated
Credit Quality Information
Recorded investment	0	0
Multi-family mortgage
Credit Quality Information
Recorded investment	932,163	847,711
Multi-family mortgage | Originated
Credit Quality Information
Recorded investment	896,482	799,813
Multi-family mortgage | Acquired
Credit Quality Information
Recorded investment	35,681	47,898
Multi-family mortgage | Pass | Originated
Credit Quality Information
Recorded investment	896,398	799,483
Multi-family mortgage | Pass | Acquired
Credit Quality Information
Recorded investment	35,681	47,715
Multi-family mortgage | OAEM | Originated
Credit Quality Information
Recorded investment	0	0
Multi-family mortgage | OAEM | Acquired
Credit Quality Information
Recorded investment	0	0
Multi-family mortgage | Substandard | Originated
Credit Quality Information
Recorded investment	84	330
Multi-family mortgage | Substandard | Acquired
Credit Quality Information
Recorded investment	0	183
Multi-family mortgage | Doubtful | Originated
Credit Quality Information
Recorded investment	0	0
Construction
Credit Quality Information
Recorded investment	246,048	173,300
Construction | Originated
Credit Quality Information
Recorded investment	239,015	151,138
Construction | Acquired
Credit Quality Information
Recorded investment	7,033	22,162
Construction | Pass | Originated
Credit Quality Information
Recorded investment	239,015	150,742
Construction | Pass | Acquired
Credit Quality Information
Recorded investment	7,033	22,162
Construction | OAEM | Originated
Credit Quality Information
Recorded investment	0	0
Construction | OAEM | Acquired
Credit Quality Information
Recorded investment	0	0
Construction | Substandard | Originated
Credit Quality Information
Recorded investment	0	396
Construction | Substandard | Acquired
Credit Quality Information
Recorded investment	0	0
Construction | Doubtful | Originated
Credit Quality Information
Recorded investment	0	0
Commercial
Credit Quality Information
Recorded investment	729,502	736,418
Commercial | Originated
Credit Quality Information
Recorded investment	713,875	712,630
Commercial | Acquired
Credit Quality Information
Recorded investment	15,627	23,788
Commercial | Pass | Originated
Credit Quality Information
Recorded investment	688,268	685,773
Commercial | Pass | Acquired
Credit Quality Information
Recorded investment	15,215	23,250
Commercial | OAEM | Originated
Credit Quality Information
Recorded investment	10,803	3,726
Commercial | OAEM | Acquired
Credit Quality Information
Recorded investment	210	236
Commercial | Substandard | Originated
Credit Quality Information
Recorded investment	14,801	22,870
Commercial | Substandard | Acquired
Credit Quality Information
Recorded investment	202	302
Commercial | Doubtful | Originated
Credit Quality Information
Recorded investment	3	261
Equipment financing
Credit Quality Information
Recorded investment	1,052,408	982,089
Equipment financing | Originated
Credit Quality Information
Recorded investment	1,049,997	978,840
Equipment financing | Acquired
Credit Quality Information
Recorded investment	2,411	3,249
Equipment financing | Pass | Originated
Credit Quality Information
Recorded investment	1,038,793	969,275
Equipment financing | Pass | Acquired
Credit Quality Information
Recorded investment	2,404	3,240
Equipment financing | OAEM | Originated
Credit Quality Information
Recorded investment	1,389	52
Equipment financing | OAEM | Acquired
Credit Quality Information
Recorded investment	0	0
Equipment financing | Substandard | Originated
Credit Quality Information
Recorded investment	7,995	6,895
Equipment financing | Substandard | Acquired
Credit Quality Information
Recorded investment	7	9
Equipment financing | Doubtful | Originated
Credit Quality Information
Recorded investment	1,820	2,618
Condominium association
Credit Quality Information
Recorded investment	56,838	50,451
Condominium association | Originated
Credit Quality Information
Recorded investment	56,838	50,451
Condominium association | Acquired
Credit Quality Information
Recorded investment	0	0
Condominium association | Pass | Originated
Credit Quality Information
Recorded investment	56,687	50,186
Condominium association | Pass | Acquired
Credit Quality Information
Recorded investment	0	0
Condominium association | OAEM | Originated
Credit Quality Information
Recorded investment	0	0
Condominium association | OAEM | Acquired
Credit Quality Information
Recorded investment	0	0
Condominium association | Substandard | Originated
Credit Quality Information
Recorded investment	151	265
Condominium association | Substandard | Acquired
Credit Quality Information
Recorded investment	0	0
Condominium association | Doubtful | Originated
Credit Quality Information
Recorded investment	0	0
Other consumer
Credit Quality Information
Recorded investment	38,782	23,370
Other consumer | Originated
Credit Quality Information
Recorded investment	38,674	23,260
Other consumer | Acquired
Credit Quality Information
Recorded investment	108	110
Other consumer | Pass | Originated
Credit Quality Information
Recorded investment	38,673	23,249
Other consumer | Pass | Acquired
Credit Quality Information
Recorded investment	108	110
Other consumer | OAEM | Originated
Credit Quality Information
Recorded investment	0	0
Other consumer | OAEM | Acquired
Credit Quality Information
Recorded investment	0	0
Other consumer | Substandard | Originated
Credit Quality Information
Recorded investment	1	11
Other consumer | Substandard | Acquired
Credit Quality Information
Recorded investment	0	0
Other consumer | Doubtful | Originated
Credit Quality Information
Recorded investment	0	0
Total
Credit Quality Information
Recorded investment		5,144,064
Total | Originated
Credit Quality Information
Recorded investment	5,394,918	4,925,036
Total | Acquired
Credit Quality Information
Recorded investment	151,834	219,028
Total | Pass
Credit Quality Information
Recorded investment	5,546,752
Total | Pass | Originated
Credit Quality Information
Recorded investment	5,337,759	4,877,085
Total | Pass | Acquired
Credit Quality Information
Recorded investment	141,801	208,396
Total | OAEM | Originated
Credit Quality Information
Recorded investment	29,198	9,874
Total | OAEM | Acquired
Credit Quality Information
Recorded investment	807	862
Total | Substandard | Originated
Credit Quality Information
Recorded investment	26,138	35,198
Total | Substandard | Acquired
Credit Quality Information
Recorded investment	9,226	9,770
Total | Doubtful | Originated
Credit Quality Information
Recorded investment	1,823	2,879
Residential mortgage
Credit Quality Information
Recorded investment	$ 814,245	$ 782,968
Percentage of loans to aggregate outstanding amount	100.00%	100.00%
Residential mortgage | Originated
Credit Quality Information
Recorded investment	$ 711,522	$ 653,059
Percentage of loans to aggregate outstanding amount	87.40%	83.40%
Residential mortgage | Acquired
Credit Quality Information
Recorded investment	$ 102,723	$ 129,909
Percentage of loans to aggregate outstanding amount	12.60%	16.60%
Residential mortgage | Loan-to-value ratio, less than 50% | Originated
Credit Quality Information
Recorded investment	$ 184,628	$ 171,523
Percentage of loans to aggregate outstanding amount	22.70%	21.90%
Residential mortgage | Loan-to-value ratio, less than 50% | Acquired
Credit Quality Information
Recorded investment	$ 32,838	$ 36,752
Percentage of loans to aggregate outstanding amount	4.00%	4.60%
Residential mortgage | Loan-to-value ratio, 50% - 69% | Originated
Credit Quality Information
Recorded investment	$ 293,976	$ 287,337
Percentage of loans to aggregate outstanding amount	36.10%	36.70%
Residential mortgage | Loan-to-value ratio, 50% - 69% | Acquired
Credit Quality Information
Recorded investment	$ 44,754	$ 53,788
Percentage of loans to aggregate outstanding amount	5.40%	6.90%
Residential mortgage | Loan-to-value ratio, 70% - 79% | Originated
Credit Quality Information
Recorded investment	$ 204,600	$ 173,870
Percentage of loans to aggregate outstanding amount	25.10%	22.20%
Residential mortgage | Loan-to-value ratio, 70% - 79% | Acquired
Credit Quality Information
Recorded investment	$ 14,305	$ 26,510
Percentage of loans to aggregate outstanding amount	1.80%	3.40%
Residential mortgage | Loan-to-value ratio, 80% and over | Originated
Credit Quality Information
Recorded investment	$ 25,664	$ 19,030
Percentage of loans to aggregate outstanding amount	3.20%	2.40%
Residential mortgage | Loan-to-value ratio, 80% and over | Acquired
Credit Quality Information
Recorded investment	$ 4,608	$ 6,701
Percentage of loans to aggregate outstanding amount	0.60%	0.90%
Residential mortgage | Data not available | Originated
Credit Quality Information
Recorded investment	$ 2,654	$ 1,299
Percentage of loans to aggregate outstanding amount	0.30%	0.20%
Residential mortgage | Data not available | Acquired
Credit Quality Information
Recorded investment	$ 6,218	$ 6,158
Percentage of loans to aggregate outstanding amount	0.80%	0.80%
Home equity
Credit Quality Information
Recorded investment	$ 376,819	$ 376,484
Percentage of loans to aggregate outstanding amount	100.00%	100.00%
Home equity | Originated
Credit Quality Information
Recorded investment	$ 343,247	$ 331,014
Percentage of loans to aggregate outstanding amount	91.00%	87.90%
Home equity | Acquired
Credit Quality Information
Recorded investment	$ 33,572	$ 45,470
Percentage of loans to aggregate outstanding amount	9.00%	12.10%
Home equity | Loan-to-value ratio, less than 50% | Originated
Credit Quality Information
Recorded investment	$ 132,736	$ 142,534
Percentage of loans to aggregate outstanding amount	35.20%	37.90%
Home equity | Loan-to-value ratio, less than 50% | Acquired
Credit Quality Information
Recorded investment	$ 16,882	$ 24,705
Percentage of loans to aggregate outstanding amount	4.50%	6.60%
Home equity | Loan-to-value ratio, 50% - 69% | Originated
Credit Quality Information
Recorded investment	$ 91,681	$ 84,423
Percentage of loans to aggregate outstanding amount	24.30%	22.40%
Home equity | Loan-to-value ratio, 50% - 69% | Acquired
Credit Quality Information
Recorded investment	$ 7,958	$ 10,353
Percentage of loans to aggregate outstanding amount	2.10%	2.70%
Home equity | Loan-to-value ratio, 70% - 79% | Originated
Credit Quality Information
Recorded investment	$ 81,459	$ 73,898
Percentage of loans to aggregate outstanding amount	21.60%	19.60%
Home equity | Loan-to-value ratio, 70% - 79% | Acquired
Credit Quality Information
Recorded investment	$ 705	$ 1,000
Percentage of loans to aggregate outstanding amount	0.20%	0.30%
Home equity | Loan-to-value ratio, 80% and over | Originated
Credit Quality Information
Recorded investment	$ 37,371	$ 30,129
Percentage of loans to aggregate outstanding amount	9.90%	8.00%
Home equity | Loan-to-value ratio, 80% and over | Acquired
Credit Quality Information
Recorded investment	$ 4,726	$ 4,348
Percentage of loans to aggregate outstanding amount	1.30%	1.20%
Home equity | Data not available | Originated
Credit Quality Information
Recorded investment	$ 0	$ 30
Percentage of loans to aggregate outstanding amount	0.00%	0.00%
Home equity | Data not available | Acquired
Credit Quality Information
Recorded investment	$ 3,301	$ 5,064
Percentage of loans to aggregate outstanding amount	0.90%	1.30%