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Regulatory Capital Requirements (Details) - USD ($) $ in Thousands | Dec. 31, 2018 | Dec. 31, 2017
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Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] |  |
Common Equity Tier One Capital | $ 1,253,394 | $ 1,158,252
Capital Conservation Buffer | 5.992% |
Common Equity Tier 1 Capital to Risk Weighted Assets | 12.7401% | 11.7421%
Common Equity Tier One Capital Required for Capital Adequacy | $ 442,717 | $ 443,886
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 plus capital conservation buffer phase-in | $ 627,182 | $ 567,187
Common Equity Tier 1 Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets plus capital conservation buffer phase-in | 6.38% | 5.75%
Common Equity Tier One Capital Required for Capital Adequacy - minimum required plus fully phased in capital conservation buffer | $ 688,670 | $ 690,489
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%
Total Capital, Actual Amount | $ 1,376,555 | $ 1,280,326
Total Capital (to risk-weighted assets), Ratio | 13.992% | 12.9796%
Total Capital For Capital Adequacy Purposes, Amount | $ 787,052 | $ 789,130
Total Capital (to risk-weighted assets), For Capital Adequacy Purposes, Ratio | 8.00% | 8.00%
Capital Required for Capital Adequacy plus capital conservation buffer phase-in | $ 971,517 | $ 912,432
Capital Required for Capital Adequacy to Risk Weighted Assets plus capital conservation buffer phase-in | 9.88% | 9.25%
Capital Required for Capital Adequacy plus capital conservation buffer fully phased-in | $ 1,033,006 | $ 1,035,734
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 | $ 1,253,394 | $ 1,165,903
Tier 1 Capital (to risk-weighted assets), Ratio | 12.7401% | 11.8196%
Tier 1 Capital For Capital Adequacy Purposes, Amount | $ 590,289 | $ 591,848
Tier 1 Capital (to risk-weighted assets) For Capital Adequacy Purposes, Ratio | 6.00% | 6.00%
Tier One Risk Based Capital Required for Capital Adequacy plus capital conservation buffer phase-in | $ 774,754 | $ 715,149
Tier One Based Capital Required for Capital Adequacy to Risk Weighted Assets plus capital conservation buffer phase-in | 7.88% | 7.25%
Tier One Risk Based Capital Required for Capital Adequacy plus capital conservation buffer fully phased-in | $ 836,243 | $ 838,451
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, Actual Amount | $ 1,253,394 | $ 1,165,903
Tier 1 Capital (to average assets), Ratio | 10.2444% | 10.9611%
Tier 1 Capital For Capital Adequacy Purposes, Amount | $ 489,399 | $ 425,469
Tier 1 Capital (to average assets) For Capital Adequacy Purposes, Ratio | 4.00% | 4.00%
Banking Subsidiaries [Member] |  |
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items] |  |
Common Equity Tier One Capital | $ 1,274,317 | $ 1,184,476
Capital Conservation Buffer | 5.8494% |
Common Equity Tier 1 Capital to Risk Weighted Assets | 12.9576% | 12.0133%
Common Equity Tier One Capital Required for Capital Adequacy | $ 442,552 | $ 443,687
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 plus capital conservation buffer phase-in | $ 626,948 | $ 566,933
Common Equity Tier 1 Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets plus capital conservation buffer phase-in | 6.38% | 5.75%
Common Equity Tier One Capital Required for Capital Adequacy - minimum required plus fully phased in capital conservation buffer | $ 688,414 | $ 690,180
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 | $ 639,241 | $ 640,881
Common Equity Tier 1 Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets | 6.50% | 6.50%
Total Capital, Actual Amount | $ 1,362,016 | $ 1,263,252
Total Capital (to risk-weighted assets), Ratio | 13.8494% | 12.8123%
Total Capital For Capital Adequacy Purposes, Amount | $ 786,759 | $ 788,777
Total Capital (to risk-weighted assets), For Capital Adequacy Purposes, Ratio | 8.00% | 8.00%
Capital Required for Capital Adequacy plus capital conservation buffer phase-in | $ 971,155 | $ 912,023
Capital Required for Capital Adequacy to Risk Weighted Assets plus capital conservation buffer phase-in | 9.88% | 9.25%
Capital Required for Capital Adequacy plus capital conservation buffer fully phased-in | $ 1,032,621 | $ 1,035,269
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 | $ 983,448 | $ 985,971
Total Capital (to risk-weighted assets) To Be Well Capitalized Under Prompt Corrective Action Provision | 10.00% | 10.00%
Tier 1 Capital, Actual Amount | $ 1,274,317 | $ 1,184,476
Tier 1 Capital (to risk-weighted assets), Ratio | 12.9576% | 12.0133%
Tier 1 Capital For Capital Adequacy Purposes, Amount | $ 590,069 | $ 591,582
Tier 1 Capital (to risk-weighted assets) For Capital Adequacy Purposes, Ratio | 6.00% | 6.00%
Tier One Risk Based Capital Required for Capital Adequacy plus capital conservation buffer phase-in | $ 774,465 | $ 714,829
Tier One Based Capital Required for Capital Adequacy to Risk Weighted Assets plus capital conservation buffer phase-in | 7.88% | 7.25%
Tier One Risk Based Capital Required for Capital Adequacy plus capital conservation buffer fully phased-in | $ 835,931 | $ 838,075
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 | $ 786,759 | $ 788,777
Tier 1 Capital (to risk-weighted assets) To Be Well Capitalized Under Prompt Corrective Action Provision, Ratio | 8.00% | 8.00%
Tier 1 Capital, Actual Amount | $ 1,274,317 | $ 1,184,476
Tier 1 Capital (to average assets), Ratio | 10.4185% | 10.8186%
Tier 1 Capital For Capital Adequacy Purposes, Amount | $ 489,254 | $ 437,939
Tier 1 Capital (to average assets) For Capital Adequacy Purposes, Ratio | 4.00% | 4.00%
Tier 1 Capital To Be Well Capitalized Under Prompt Corrective Provision, Amount | $ 611,567 | $ 547,423
Tier 1 Capital (to average assets) To Be Well Capitalized Under Prompt Corrective Provision, Ratio | 5.00% | 5.00%

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- Definition Tier 1 Leverage Capital as defined in the regulations. Also called Core Capital. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958568-112826 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=84167132&loc=d3e65071-112826 + Details
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- Definition The minimum Tier One Capital Ratio (Tier one capital divided by risk-weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958570-112826 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958568-112826 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=84167132&loc=d3e65071-112826 + Details
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- Definition The amount of Tier 1 Risk Based Capital required to be categorized as well capitalized under the regulatory framework for prompt corrective action. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958568-112826 + Details
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- Definition The Tier 1 capital ratio (Tier 1 capital divided by risk weighted assets) required to be categorized as "well capitalized" under the regulatory framework for prompt corrective action. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958568-112826 + Details
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- Definition Tier 1 capital divided by risk weighted assets as defined by regulations. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1H -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=84167132&loc=d3e65071-112826 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 505 -Section 50 -Paragraph 1 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=84167132&loc=SL5958568-112826 + Details
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