Basis of Presentation (Details) $ in Thousands	Jun. 01, 2020 USD ($) office	May 29, 2020 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Business Acquisition [Line Items]
Total assets			$ 20,173,298	$ 19,736,544
Loans held for investment			13,117,392	13,236,433
Total deposits			$ 16,740,007	$ 16,214,177
Opus Bank
Business Acquisition [Line Items]
Total merger consideration	$ 749,605	$ 749,605
Opus Bank | Opus Bank
Business Acquisition [Line Items]
Total assets	8,320,000
Loans held for investment	5,940,000
Total deposits	$ 6,910,000
Number of banking offices | office	46