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Regulatory Capital Requirements (Details) - USD ($) $ in Thousands | Dec. 31, 2020 | Dec. 31, 2019
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Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] |  |
Capital Conservation Buffer | 6.45% |
Common Equity Tier One Capital | $ 1,390,958 | $ 1,317,202
Common Equity Tier 1 Capital to Risk Weighted Assets | 12.88% | 12.45%
Common Equity Tier One Capital Required for Capital Adequacy | $ 486,080 | $ 476,260
Common Equity Tier 1 Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets | 4.50% | 4.50%
Common Equity Tier One Capital Required for Capital Adequacy - minimum required plus fully phased in capital conservation buffer | $ 756,125 | $ 740,849
Common Equity Tier 1 Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets plus capital conservation buffer fully phased-in | 7.00% | 7.00%
Tier 1 Capital, Actual Amount | $ 1,390,958 | $ 1,317,202
Tier 1 Capital (to risk-weighted assets), Ratio | 0.1288 | 0.1245
Tier 1 Capital For Capital Adequacy Purposes, Amount | $ 648,107 | $ 635,014
Tier 1 Capital (to risk-weighted assets) For Capital Adequacy Purposes, Ratio | 0.0600 | 0.0600
Tier One Risk Based Capital Required for Capital Adequacy plus capital conservation buffer fully phased-in | $ 918,152 | $ 899,603
Tier One Based Capital Required for Capital Adequacy to Risk Weighted Assets plus capital conservation buffer fully phased-in | 8.50% | 8.50%
Total Capital, Actual Amount | $ 1,561,020 | $ 1,439,877
Total Capital (to risk-weighted assets), Ratio | 0.1445 | 0.1360
Total Capital For Capital Adequacy Purposes, Amount | $ 864,143 | $ 846,685
Total Capital (to risk-weighted assets), For Capital Adequacy Purposes, Ratio | 0.0800 | 0.0800
Capital Required for Capital Adequacy plus capital conservation buffer fully phased-in | $ 1,134,187 | $ 1,111,274
Capital Required for Capital Adequacy to Risk Weighted Assets plus capital conservation buffer fully phased-in | 10.50% | 10.50%
Tier 1 Capital, Actual Amount | $ 1,390,958 | $ 1,317,202
Tier 1 Capital (to average assets), Ratio | 0.0886 | 0.1017
Tier 1 Capital For Capital Adequacy Purposes, Amount | $ 628,112 | $ 517,938
Tier 1 Capital (to average assets) For Capital Adequacy Purposes, Ratio | 0.0400 | 0.0400
Banking Subsidiaries |  |
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] |  |
Capital Conservation Buffer | 6.33% |
Common Equity Tier One Capital | $ 1,411,834 | $ 1,318,044
Common Equity Tier 1 Capital to Risk Weighted Assets | 13.08% | 12.46%
Common Equity Tier One Capital Required for Capital Adequacy | $ 485,775 | $ 475,913
Common Equity Tier 1 Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets | 4.50% | 4.50%
Common Equity Tier One Capital Required for Capital Adequacy - minimum required plus fully phased in capital conservation buffer | $ 755,651 | $ 740,310
Common Equity Tier 1 Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets plus capital conservation buffer fully phased-in | 7.00% | 7.00%
Common Equity Tier One Risk Based Capital Required to be Well Capitalized | $ 701,676 | $ 687,430
Common Equity Tier 1 Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets | 6.50% | 6.50%
Tier 1 Capital, Actual Amount | $ 1,411,834 | $ 1,318,044
Tier 1 Capital (to risk-weighted assets), Ratio | 0.1308 | 0.1246
Tier 1 Capital For Capital Adequacy Purposes, Amount | $ 647,700 | $ 634,551
Tier 1 Capital (to risk-weighted assets) For Capital Adequacy Purposes, Ratio | 0.0600 | 0.0600
Tier One Risk Based Capital Required for Capital Adequacy plus capital conservation buffer fully phased-in | $ 917,576 | $ 898,947
Tier One Based Capital Required for Capital Adequacy to Risk Weighted Assets plus capital conservation buffer fully phased-in | 8.50% | 8.50%
Tier 1 Capital To Be Well Capitalized Under Prompt Corrective Action Provision, Amount | $ 863,601 | $ 846,068
Tier 1 Capital (to risk-weighted assets) To Be Well Capitalized Under Prompt Corrective Action Provision, Ratio | 0.0800 | 0.0800
Total Capital, Actual Amount | $ 1,546,804 | $ 1,405,422
Total Capital (to risk-weighted assets), Ratio | 0.1433 | 0.1329
Total Capital For Capital Adequacy Purposes, Amount | $ 863,601 | $ 846,068
Total Capital (to risk-weighted assets), For Capital Adequacy Purposes, Ratio | 0.0800 | 0.0800
Capital Required for Capital Adequacy plus capital conservation buffer fully phased-in | $ 1,133,476 | $ 1,110,464
Capital Required for Capital Adequacy to Risk Weighted Assets plus capital conservation buffer fully phased-in | 10.50% | 10.50%
Total Capital To Be Well Capitalized Under Prompt Corrective Action Provision, Amount | $ 1,079,501 | $ 1,057,585
Total Capital (to risk-weighted assets) To Be Well Capitalized Under Prompt Corrective Action Provision | 0.1000 | 0.1000
Tier 1 Capital, Actual Amount | $ 1,411,834 | $ 1,318,044
Tier 1 Capital (to average assets), Ratio | 0.0908 | 0.1022
Tier 1 Capital For Capital Adequacy Purposes, Amount | $ 622,171 | $ 515,797
Tier 1 Capital (to average assets) For Capital Adequacy Purposes, Ratio | 0.0400 | 0.0400
Tier 1 Capital To Be Well Capitalized Under Prompt Corrective Provision, Amount | $ 777,714 | $ 644,746
Tier 1 Capital (to average assets) To Be Well Capitalized Under Prompt Corrective Provision, Ratio | 0.0500 | 0.0500

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