Fair Value Measurements - Narrative (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans not covered under loss-share agreements	$ 16,141			$ 36,990
Specific reserve included in allowance for loan losses	172,354	$ 145,387	$ 173,106	176,144	$ 120,185	$ 52,162
Valuation adjustment to mortgage servicing rights	(13,561)	14,522
Changes in fair value, gain (loss)	(7,520)	$ 9,617
Impaired Loans, not covered
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Specific reserve included in allowance for loan losses	$ 4,991			$ 12,845