Retirement And Other Benefit Plans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Retirement Benefits [Abstract]
Employer contributions to defined contribution plan	$ 6,800	$ 4,200	$ 3,100
Deferred Compensation Arrangement with Individual, Postretirement Benefits
Other long-term liabilities	66,528	61,176
Accrued expenses and other current liabilities	$ 27,020	29,305
Deferred compensation, percentage of funds invested	85.00%
Deferred Compensation
Deferred Compensation Arrangement with Individual, Postretirement Benefits
Compensation deferred by participants	$ 6,900	4,900	2,300
Amount withdrawn from the Plan by participants	200	200	$ 1,500
Other long-term liabilities	25,900	20,700
Accrued expenses and other current liabilities	400	200
Life insurance contract assets	$ 22,200	$ 18,200