Summary of Significant Accounting Policies, Other Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Other Liabilities [Abstract]
Deferred tax liabilities	$ 626	$ 10,741
Reserve for other tax liabilities	22,731	17,121
Liability for deferred compensation plan	47,543	43,238
Pension plan benefits reserve	2,981	3,454
Finance lease liabilities	7,728	0
Asset retirement obligation	6,717	6,631
Other	13,955	15,610
Total other liabilities	$ 102,281	$ 96,795