Employee Benefits - Additional Information (Details) - USD ($)		12 Months Ended
	Jun. 01, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Prior service cost or loss amortization		$ 0
Amount recognized in accumulated other comprehensive income, expected to be recognized as a component of net periodic benefit cost in 2019		$ 20,000
Asset Allocations		100.00%	100.00%
Minimum cash contribution		$ 0	$ 1,300,000	$ 900,000
Amount recognized in compensation expense		$ 154,905,000	139,118,000	125,068,000
2018 Employee Stock Purchase Plan | Common Class A
Defined Benefit Plan Disclosure [Line Items]
Percentage of discount on fair market value of common stock	15.00%	15.00%
Common stock shares issued		40,598
Equity-based compensation expense		$ 205,000
Plan 401 K
Defined Benefit Plan Disclosure [Line Items]
Plan contributions		3,800,000	3,500,000
Plan 401 K | Supplemental Employee Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Accrued liability		1,700,000	1,900,000
Amount recognized in compensation expense		300,000	706,000	322,000
Plan 401 K | Unqualified Supplemental Retirement and Voluntary Deferred Compensation Plan
Defined Benefit Plan Disclosure [Line Items]
Accrued liability		3,100,000	3,200,000
Amount recognized in compensation expense		80,000	47,000	$ 186,000
Deferred compensation		$ 3,100,000	$ 3,200,000
Maximum | 2018 Employee Stock Purchase Plan | Common Class A
Defined Benefit Plan Disclosure [Line Items]
Amount of common stock may be granted	500,000
Scenario, Forecast | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Minimum cash contribution					$ 0
Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Asset Allocations		59.00%	55.00%
Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Asset Allocations		40.00%	39.00%
Other Securities
Defined Benefit Plan Disclosure [Line Items]
Asset Allocations		1.00%