Employee Benefit Plans Schedule of Defined Benefit Plan Activity (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Amounts recognized in the consolidated balance sheets:
Prepaid pension costs	$ 25,032	$ 26,080
Non-current employee benefits	(49,314)	(47,917)
Pension Plans [Member]
Change in benefit obligation:
Benefit obligation at January 1	(150,911)	(153,716)
Service cost	(523)	(1,170)	(1,275)
Interest cost	(6,196)	(5,518)	(6,513)
Plan settlement	0	1,819
Benefits paid	10,207	10,510
Expenses paid	322	350
Actuarial (gain) loss	(3,098)	(3,186)
Benefit obligation at December 31	(150,199)	(150,911)	(153,716)
Change in plan assets:
Balance as of January 1	137,036	128,060
Actual return on plan assets	7,162	19,482
Plan settlement	0	(1,819)
Expenses paid	(322)	(350)
Contributions	348	2,173
Benefits paid	(10,207)	(10,510)
Balance as of December 31	134,017	137,036	128,060
Funded status at December 31	(16,182)	(13,875)
Amounts recognized in the consolidated balance sheets:
Prepaid pension costs	25,032	26,080
Other accrued liabilities	(324)	(342)
Non-current employee benefits	(40,890)	(39,613)
Net amounts recognized	(16,182)	(13,875)
Other Postretirement Benefits [Member]
Change in benefit obligation:
Benefit obligation at January 1	(8,899)	(10,158)
Service cost	(9)	(16)	(14)
Interest cost	(430)	(418)	(465)
Plan settlement	0	0
Benefits paid	552	560
Expenses paid	0	0
Actuarial (gain) loss	(245)	1,133
Benefit obligation at December 31	(9,031)	(8,899)	(10,158)
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	552	560
Benefits paid	(552)	(560)
Balance as of December 31	0	0	0
Funded status at December 31	(9,031)	(8,899)
Amounts recognized in the consolidated balance sheets:
Prepaid pension costs	0	0
Other accrued liabilities	(607)	(597)
Non-current employee benefits	(8,424)	(8,304)
Net amounts recognized	$ (9,031)	$ (8,901)