Pension and Other Post-Retirement Plans (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended			1 Months Ended	12 Months Ended
	Dec. 31, 2012 Defined benefit pension plans	Dec. 31, 2011 Defined benefit pension plans	Dec. 31, 2010 Defined benefit pension plans	Nov. 30, 2011 Supplemental Executive Retirement Plan	Dec. 31, 2012 Supplemental Executive Retirement Plan	Dec. 31, 2010 Supplemental Executive Retirement Plan
Pension and Other Post-Retirement Plans
Estimated contributions in the next fiscal year		$ 3,892
Compounded annual growth rate (as a percent)					4.00%
Curtailments	0	0	1,692	3,101
Cash value in government fund accounts				902		902
Cash value of the life insurance policies				$ 2,199		$ 2,228