Employee Benefit Plans Schedule of Defined Benefit Plan Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Amounts recognized in the consolidated balance sheets:
Prepaid pension costs	$ 20,650	$ 25,032
Non-current employee benefit liabilities	(55,055)	(49,314)
Pension Plans [Member]
Change in benefit obligation:
Benefit obligation at January 1	(150,199)	(150,911)
Service cost	(532)	(523)	$ (1,170)
Interest cost	(4,992)	(6,196)	(5,518)
Plan settlement	17,047	0
Special termination benefits	(3,831)	0	0
Benefits paid	9,879	10,207
Expenses paid	490	322
Actuarial (gain) loss	(1,368)	(3,098)
Benefit obligation at December 31	(133,506)	(150,199)	(150,911)
Change in plan assets:
Balance as of January 1	134,017	137,036
Actual return on plan assets	(327)	7,162
Plan settlement	(17,047)	0
Expenses paid	(490)	(322)
Contributions	346	348
Benefits paid	(9,879)	(10,207)
Balance as of December 31	106,620	134,017	137,036
Unfunded status at December 31	(26,886)	(16,182)
Amounts recognized in the consolidated balance sheets:
Prepaid pension costs	20,650	25,032
Other accrued liabilities	(320)	(324)
Non-current employee benefit liabilities	(47,216)	(40,890)
Net amounts recognized	(26,886)	(16,182)
Other Postretirement Benefits [Member]
Change in benefit obligation:
Benefit obligation at January 1	(9,031)	(8,899)
Service cost	(8)	(9)	(16)
Interest cost	(371)	(430)	(418)
Plan settlement	0	0
Special termination benefits	0	0	0
Benefits paid	522	552
Expenses paid	0	0
Actuarial (gain) loss	454	(245)
Benefit obligation at December 31	(8,434)	(9,031)	(8,899)
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	522	552
Benefits paid	(522)	(552)
Balance as of December 31	0	0	$ 0
Unfunded status at December 31	(8,434)	(9,031)
Amounts recognized in the consolidated balance sheets:
Prepaid pension costs	0	0
Other accrued liabilities	(595)	(607)
Non-current employee benefit liabilities	(7,839)	(8,424)
Net amounts recognized	$ (8,434)	$ (9,031)