Pensions and Other Post-Employment Benefits (Details 1) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Pension Benefits [Member]
Net benefit cost
Service cost	$ 7,963	$ 9,724	$ 7,915
Interest cost	10,339	9,936	9,912
Expected return on plan assets	(12,419)	(12,261)	(11,934)
Amortization of prior service cost (benefit)	(434)	(340)	(335)
Recognized net actuarial loss	5,263	7,912	5,605
Net periodic cost	10,712	14,971	11,163
Settlements	7	0	0
Total net benefit cost	10,719	14,971	11,163
Change in other comprehensive income
OCI at beginning of year	77,249	124,955	104,056
Increase (decrease) in OCI:
Recognized during year — prior service cost (credit)	434	340	335
Recognized during year — net actuarial (losses) gains	(5,263)	(7,912)	(5,605)
Occurring during year — prior service cost	0	0	117
Occurring during year — net actuarial losses (gains)	49,037	(40,143)	25,995
Other adjustments	0	(3)	0
Foreign currency exchange rate changes	(116)	12	57
OCI at end of year	121,341	77,249	124,955
Other Benefits [Member]
Net benefit cost
Service cost	138	305	285
Interest cost	675	1,243	1,439
Expected return on plan assets	0	0	0
Amortization of prior service cost (benefit)	(1,498)	115	87
Recognized net actuarial loss	0	0	0
Net periodic cost	(685)	1,663	1,811
Settlements	0	0	0
Total net benefit cost	(685)	1,663	1,811
Change in other comprehensive income
OCI at beginning of year	52	2,587	1,180
Increase (decrease) in OCI:
Recognized during year — prior service cost (credit)	1,498	(115)	(87)
Recognized during year — net actuarial (losses) gains	0	0	0
Occurring during year — prior service cost	(14,034)	0	0
Occurring during year — net actuarial losses (gains)	223	(2,397)	1,494
Other adjustments	0	(23)	0
Foreign currency exchange rate changes	0	0	0
OCI at end of year	$ (12,261)	$ 52	$ 2,587