Summary of Significant Accounting Policies Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Sep. 30, 2020	Jan. 01, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Held to maturity allowance for credit loss		$ 70	$ 61
Retained Earnings (Accumulated Deficit)		2,424,992		$ 2,380,867
Allowance for Unfunded Commitments		57,276		21,907
Allowance for Loan Losses				201,371
Cumulative Effect, Period Of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for Loan Losses			131,147
Allowance for Loan Losses [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for Loan Losses		384,711		201,371
SEC Schedule, 12-09, Reserve, Off-balance Sheet Activity [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for Unfunded Commitments		$ 57,276		$ 21,907
Accounting Standards Update 2016-13
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained Earnings (Accumulated Deficit)			98,000
Deferred Income Tax Assets, Net			33,000
Accounting Standards Update 2016-13 | Forecast
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reasonable and Supportable Period 2016-13	2 years
Accounting Standards Update 2016-13 | Cumulative Effect, Period Of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for Unfunded Commitments			18,690
Accounting Standards Update 2016-13 | Allowance for Loan Losses [Member] | Cumulative Effect, Period Of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for Loan Losses			112,457
Accounting Standards Update 2016-13 | SEC Schedule, 12-09, Reserve, Off-balance Sheet Activity [Member] | Cumulative Effect, Period Of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for Unfunded Commitments			18,690
Accounting Standards Update 2016-13 | Allowance for Loans Losses and Unfunded Commitments [Member] | Cumulative Effect, Period Of Adoption, Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for Loan Losses			$ 131,000