Salary Deferral Plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Deferred Compensation Arrangements [Abstract]
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent	50.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	4.00%
Percentage of employee self-directed contributions matched by employer	100.00%
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Compensation expense	$ 9,400	$ 8,100	$ 7,600
Other liabilities	411,074	288,569
Supplemental Employee Retirement Plan
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Other liabilities	29,800	$ 29,200
SERP covered by Rabbi Trust
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]
Other liabilities	$ 17,300