Basis of Presentation (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated deficit	$ 3,430,135		$ 917,227
Allowance for credit losses on debt securities held to maturity	15,017	$ 1,892	0
Allowance for credit losses on loans	$ 1,754,352	1,351,072	920,993	$ 977,660	$ 966,022	$ 885,242
Allowance for credit losses on letters of credit and unfunded commitments			66,955
As Reported Under ASC 326
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for credit losses on debt securities held to maturity			1,847
Allowance for credit losses on loans			1,105,924
Allowance for credit losses on letters of credit and unfunded commitments			76,946
Impact of ASC 326 Adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated deficit			150,200
Allowance for credit losses on debt securities held to maturity		$ 0	1,847
Allowance for credit losses on loans			184,931
Allowance for credit losses on letters of credit and unfunded commitments			$ 9,991