Employee Benefit Plans (Schedule of Defined Benefit Plan Activity) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Amounts recognized in the consolidated balance sheets:
Non-current employee benefit liabilities	$ (67,853)	$ (61,288)
Pension Benefits
Change in benefit obligation:
Benefit obligation at January 1	(123,165)	(132,722)
Service cost	(533)	(587)	$ (564)
Interest cost	(4,860)	(4,495)	(5,059)
Plan amendment	0	0
Benefits paid	7,696	8,524
Expenses paid	391	260
Actuarial gain	(8,526)	5,855
Benefit obligation at December 31	(128,997)	(123,165)	(132,722)
Change in plan assets:
Balance as of January 1	93,167	106,192
Actual return on plan assets	15,788	(4,497)
Expenses paid	(391)	(260)
Contributions	183	256
Benefits paid	(7,696)	(8,524)
Balance as of December 31	101,051	93,167	106,192
Unfunded status at December 31	(27,946)	(29,998)
Amounts recognized in the consolidated balance sheets:
Prepaid pension costs	31,686	23,869
Other accrued liabilities	(111)	(228)
Non-current employee benefit liabilities	(59,521)	(53,639)
Net amounts recognized	(27,946)	(29,998)
Other Postretirement Benefits
Change in benefit obligation:
Benefit obligation at January 1	(8,296)	(8,967)
Service cost	(3)	(4)	(5)
Interest cost	(347)	(330)	(368)
Plan amendment	0	(39)
Benefits paid	594	553
Expenses paid	0	0
Actuarial gain	(934)	491
Benefit obligation at December 31	(8,986)	(8,296)	(8,967)
Change in plan assets:
Balance as of January 1	0	0
Actual return on plan assets	0	0
Expenses paid	0	0
Contributions	594	553
Benefits paid	(594)	(553)
Balance as of December 31	0	0	$ 0
Unfunded status at December 31	(8,986)	(8,296)
Amounts recognized in the consolidated balance sheets:
Prepaid pension costs	0	0
Other accrued liabilities	(654)	(647)
Non-current employee benefit liabilities	(8,332)	(7,649)
Net amounts recognized	$ (8,986)	$ (8,296)