Other Long-Term Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Other Liabilities Disclosure [Abstract]
Deferred compensation plan	$ 27,857	$ 25,672
Supplemental executive retirement plan	15,466	15,035
Operating lease liabilities	10,941	0
Interest rate swap derivative instrument	115	0
Other long-term liabilities	1,231	2,802
Total Other long-term liabilities	$ 55,610	$ 43,509