Pensions and Other Post-retirement Benefits (Details 6) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Summary of fair value of company's defined benefit pension plan Level 3 assets
Beginning balance	$ 4,671	$ 4,397
Actual return:
On assets still held at reporting date	403	548
On assets sold during the period	(53)	5
Purchases, sales and settlements	(185)	(279)
Ending balance	4,836	4,671
Multi-strategy hedge funds [Member]
Summary of fair value of company's defined benefit pension plan Level 3 assets
Beginning balance	3,989	3,851
Actual return:
On assets still held at reporting date	386	376
On assets sold during the period	(57)	0
Purchases, sales and settlements	(127)	(238)
Ending balance	4,191	3,989
Private equity funds [Member]
Summary of fair value of company's defined benefit pension plan Level 3 assets
Beginning balance	682	546
Actual return:
On assets still held at reporting date	17	172
On assets sold during the period	4	5
Purchases, sales and settlements	(58)	(41)
Ending balance	$ 645	$ 682