Employee Benefit Plans (Schedule of Defined Benefit Plan Activity) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Amounts recognized in the consolidated balance sheets:
Non-current employee benefit liabilities	$ (58,958)	$ (55,055)
Pension Benefits
Change in benefit obligation:
Benefit obligation at January 1	(133,506)	(150,199)
Service cost	(547)	(532)	$ (523)
Interest cost	(5,419)	(4,992)	(6,196)
Plan settlement	0	17,047
Special termination benefits	0	(3,831)	0
Benefits paid	9,596	9,879
Expenses paid	309	490
Actuarial (gain) loss	(3,154)	(1,368)
Benefit obligation at December 31	(132,721)	(133,506)	(150,199)
Change in plan assets:
Balance as of January 1	106,620	134,017
Actual return on plan assets	6,720	(327)
Plan settlement	0	(17,047)
Expenses paid	(309)	(490)
Contributions	346	346
Benefits paid	(9,596)	(9,879)
Balance as of December 31	103,781	106,620	134,017
Unfunded status at December 31	(28,940)	(26,886)
Amounts recognized in the consolidated balance sheets:
Prepaid pension costs	22,273	20,650
Other accrued liabilities	(316)	(320)
Non-current employee benefit liabilities	(50,897)	(47,216)
Net amounts recognized	(28,940)	(26,886)
Other Postretirement Benefits
Change in benefit obligation:
Benefit obligation at January 1	(8,434)	(9,031)
Service cost	(5)	(8)	(9)
Interest cost	(385)	(371)	(430)
Plan settlement	0	0
Special termination benefits	0	0	0
Benefits paid	695	522
Expenses paid	0	0
Actuarial (gain) loss	(553)	454
Benefit obligation at December 31	(8,682)	(8,434)	(9,031)
Change in plan assets:
Balance as of January 1	0	0
Actual return on plan assets	0	0
Plan settlement	0	0
Expenses paid	0	0
Contributions	695	522
Benefits paid	(695)	(522)
Balance as of December 31	0	0	$ 0
Unfunded status at December 31	(8,682)	(8,434)
Amounts recognized in the consolidated balance sheets:
Prepaid pension costs	0	0
Other accrued liabilities	(621)	(595)
Non-current employee benefit liabilities	(8,061)	(7,839)
Net amounts recognized	$ (8,682)	$ (8,434)