Loans and Allowance for Credit Losses Past Due Loan Status and Non-Accrual Loans by Portfolio Segment (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Financing Receivable, Past Due [Line Items]
≥ 90 Days Past Due and Accruing	$ 14,767	$ 16,057
Non- accrual	125,037	125,098
Current	18,514,573	16,620,575
Net Loans	18,704,722	16,837,526	$ 16,368,458
Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	39,485	56,326
Financial Asset, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	10,860	19,470
Real estate - commercial mortgage
Financing Receivable, Past Due [Line Items]
≥ 90 Days Past Due and Accruing	1,599	4,113
Non- accrual	40,775	33,166
Current	6,874,941	6,651,042
Net Loans	6,934,936	6,700,776	6,497,973
Real estate - commercial mortgage | Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	16,431	10,912
Real estate - commercial mortgage | Financial Asset, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	1,190	1,543
Commercial and industrial
Financing Receivable, Past Due [Line Items]
≥ 90 Days Past Due and Accruing	351	1,385
Non- accrual	39,379	48,106
Current	5,927,286	4,392,278
Net Loans	5,971,201	4,446,701	4,365,248
Commercial and industrial | Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	2,970	2,302
Commercial and industrial | Financial Asset, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	1,215	2,630
Real-estate - home equity
Financing Receivable, Past Due [Line Items]
≥ 90 Days Past Due and Accruing	3,889	3,564
Non- accrual	7,688	7,004
Current	1,234,854	1,292,035
Net Loans	1,251,455	1,314,944	1,386,974
Real-estate - home equity | Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	3,431	9,635
Real-estate - home equity | Financial Asset, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	1,593	2,706
Real estate - residential mortgage
Financing Receivable, Past Due [Line Items]
≥ 90 Days Past Due and Accruing	5,997	5,735
Non- accrual	16,890	16,676
Current	2,822,177	2,584,763
Net Loans	2,862,226	2,641,465	2,451,966
Real estate - residential mortgage | Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	11,401	26,982
Real estate - residential mortgage | Financial Asset, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	5,761	7,309
Real-estate - construction
Financing Receivable, Past Due [Line Items]
≥ 90 Days Past Due and Accruing	1,043	688
Non- accrual	3,482	3,618
Current	965,364	964,158
Net Loans	972,909	971,079	922,547
Real-estate - construction | Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	2,606	1,715
Real-estate - construction | Financial Asset, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	414	900
Consumer
Financing Receivable, Past Due [Line Items]
≥ 90 Days Past Due and Accruing	334	458
Non- accrual	0	0
Current	462,954	457,556
Net Loans	465,610	463,164	452,874
Consumer | Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	1,851	4,228
Consumer | Financial Asset, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	471	922
Equipment lease financing, other and overdrafts
Financing Receivable, Past Due [Line Items]
≥ 90 Days Past Due and Accruing	1,554	114
Non- accrual	16,823	16,528
Current	226,997	278,743
Net Loans	246,385	299,397	$ 290,876
Equipment lease financing, other and overdrafts | Financial Asset, 30 to 59 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	795	552
Equipment lease financing, other and overdrafts | Financial Asset, 60 to 89 Days Past Due
Financing Receivable, Past Due [Line Items]
Total Past Due and Non-accrual	$ 216	$ 3,460