Employee Benefit Plans - Profit Sharing and Savings Plans (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits
Eligibility requirement, service hours to be completed	20 hours
Deferred Profit Sharing
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits
Eligibility requirement, requisite service period	2 years
Compensation expense	$ 2,400,000	$ 1,600,000	$ 2,700,000
Savings Plan, Employee Elected
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits
Compensation expense	6,300,000	$ 5,500,000	$ 4,800,000
Maximum annual contribution per employee, amount per dollar of employee contribution	$ 1.25
Maximum annual contribution per employee, percent	4.00%