Recent Accounting Pronouncements (Details) - USD ($) $ in Thousands			3 Months Ended	12 Months Ended
		Dec. 31, 2019	Mar. 31, 2021	Dec. 31, 2019	Dec. 31, 2020	Mar. 31, 2020
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for loan losses		$ (71,982)	$ (74,010)	$ (71,982)	$ (81,238)	$ (68,211)
Off-balance sheet, credit loss, credit loss expense (reversal)			2,000
Increase in retained earnings		819,018	$ 858,423	$ 819,018	$ 868,008	$ 828,792
Accounting Standards Update [Extensible List]			us-gaap:AccountingStandardsUpdate201613Member	us-gaap:AccountingStandardsUpdate201613Member
Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for loan losses		20,385		$ 20,385
Off-balance sheet, credit loss, credit loss expense (reversal)		1,400
Increase in retained earnings	[1]	$ 13,492		$ 13,492

[1] Impact due to the adoption of ASU 2016-13, Financial Instruments (Topic 326) (“ASU 2016-13”). See Part I. Item 1. “Notes to Unaudited Consolidated Financial Statements - Note 15: Recent Accounting Pronouncements.”