Pension Plan and Postretirement Benefits Other Than Pension (Details 3) (USD $) In Thousands, unless otherwise specified																																12 Months Ended
	Dec. 31, 2010	Dec. 31, 2011 Pension Benefits	Dec. 31, 2010 Pension Benefits	Dec. 31, 2009 Pension Benefits	Dec. 31, 2008 Pension Benefits	Dec. 31, 2011 Pension Benefits Equity securities: Domestic	Dec. 31, 2010 Pension Benefits Equity securities: Domestic	Dec. 31, 2011 Pension Benefits Equity securities: Foreign	Dec. 31, 2010 Pension Benefits Equity securities: Foreign	Dec. 31, 2010 Pension Benefits Fixed income securities: Foreign bonds	Dec. 31, 2011 Pension Benefits Fixed income securities: Mortgage-backed securities	Dec. 31, 2010 Pension Benefits Fixed income securities: Mortgage-backed securities	Dec. 31, 2011 Pension Benefits Gold bullion	Dec. 31, 2010 Pension Benefits Gold bullion	Dec. 31, 2011 Pension Benefits Total investment securities	Dec. 31, 2010 Pension Benefits Total investment securities	Dec. 31, 2011 Pension Benefits Cash and other	Dec. 31, 2010 Pension Benefits Cash and other	Dec. 31, 2011 Pension Benefits Level 1 Equity securities: Domestic	Dec. 31, 2010 Pension Benefits Level 1 Equity securities: Domestic	Dec. 31, 2011 Pension Benefits Level 1 Equity securities: Foreign	Dec. 31, 2010 Pension Benefits Level 1 Equity securities: Foreign	Dec. 31, 2011 Pension Benefits Level 1 Gold bullion	Dec. 31, 2010 Pension Benefits Level 1 Gold bullion	Dec. 31, 2011 Pension Benefits Level 1 Total investment securities	Dec. 31, 2010 Pension Benefits Level 1 Total investment securities	Dec. 31, 2010 Pension Benefits Level 2 Fixed income securities: Foreign bonds	Dec. 31, 2011 Pension Benefits Level 2 Fixed income securities: Mortgage-backed securities	Dec. 31, 2010 Pension Benefits Level 2 Fixed income securities: Mortgage-backed securities	Dec. 31, 2011 Pension Benefits Level 2 Total investment securities	Dec. 31, 2010 Pension Benefits Level 2 Total investment securities	Dec. 31, 2009 Pension Benefits Level 3 Options
Pension Plan and Postretirement Benefits Other than Pension
Total fair value	$ 106,568	$ 103,404	$ 106,568	$ 91,551	$ 78,020	$ 44,818	$ 36,488	$ 38,942	$ 49,864	$ 73	$ 98	$ 130	$ 12,857	$ 14,382	$ 96,715	$ 100,937	$ 6,689	$ 5,631	$ 44,818	$ 36,488	$ 38,942	$ 49,864	$ 12,857	$ 14,382	$ 96,617	$ 100,734	$ 73	$ 98	$ 130	$ 98	$ 203
Summary of the activity of plan assets categorized as Level 3 during the period
Fair value of plan assets at beginning of year	106,568	103,404	106,568	91,551	78,020	44,818	36,488	38,942	49,864	73	98	130	12,857	14,382	96,715	100,937	6,689	5,631	44,818	36,488	38,942	49,864	12,857	14,382	96,617	100,734	73	98	130	98	203	(11)
Purchases, issuances and settlements																																262
Actual return on plan assets, sold during the period																																(123)
Proceeds from sales																																(128)
Fair value of plan assets at end of year	$ 106,568	$ 103,404	$ 106,568	$ 91,551	$ 78,020	$ 44,818	$ 36,488	$ 38,942	$ 49,864	$ 73	$ 98	$ 130	$ 12,857	$ 14,382	$ 96,715	$ 100,937	$ 6,689	$ 5,631	$ 44,818	$ 36,488	$ 38,942	$ 49,864	$ 12,857	$ 14,382	$ 96,617	$ 100,734	$ 73	$ 98	$ 130	$ 98	$ 203