Pensions and Other Post-Employment Benefits (Details 6) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Summary of fair value of company's defined benefit pension plan Level 3 assets
Beginning balance	$ 5,884	$ 4,836
Actual return:
On assets still held at reporting date	(406)	1,183
On assets sold during the period	(20)	229
Purchases, sales and settlements	6,371	(364)
Ending balance	11,829	5,884
Multi-strategy hedge funds [Member]
Summary of fair value of company's defined benefit pension plan Level 3 assets
Beginning balance	5,467	4,191
Actual return:
On assets still held at reporting date	(505)	1,276
On assets sold during the period	0	0
Purchases, sales and settlements	0	0
Ending balance	4,962	5,467
Private equity funds [Member]
Summary of fair value of company's defined benefit pension plan Level 3 assets
Beginning balance	417	645
Actual return:
On assets still held at reporting date	(14)	(93)
On assets sold during the period	(20)	229
Purchases, sales and settlements	(129)	(364)
Ending balance	254	417
Pooled Investment Fund [Member]
Summary of fair value of company's defined benefit pension plan Level 3 assets
Beginning balance	0	0
Actual return:
On assets still held at reporting date	113	0
On assets sold during the period	0	0
Purchases, sales and settlements	6,500	0
Ending balance	$ 6,613	$ 0