Postretirement Benefits Other Than Pensions (Tables)

12 Months Ended

Dec. 31, 2011

Postretirement Benefits Other Than Pensions (Tables) [Abstract]

Change in benefit obligation of the postretirement plans to the accrued postretirement liability

	2011			2010
Benefit obligation at beginning of year	$	19,937		$	17,354
Service cost		46			51
Interest cost		1,052			1,045
Actuarial loss		5,492			2,335
Amendments		(1,075	)		—
Benefits paid		(831	)		(848	)
Benefit obligation at end of year	$	24,621		$	19,937

Net postretirement benefit expense components

	2011			2010			2009
Service cost	$	46		$	51		$	62
Interest cost		1,052			1,045			966
Recognized net actuarial (gain) loss		2			—			(183	)
Amortization of prior service cost		(434	)		—			—
Amortization of curtailment gain		(244	)		(244	)		(244	)
Net postretirement benefit expense	$	422		$	852		$	601

Weighted-average assumptions used to determine the benefit obligation

	2011			2010			2009
Discount rate		4.21	%		5.29	%		5.77	%
Measurement date		12/31/2011			12/31/2010			12/31/2009

Weighted-average assumptions used to determine the net postretirement benefit expense

	2011			2010			2009
Discount rate		5.29	%		5.77	%		6.10	%
Measurement date		12/31/2011			12/31/2010			12/31/2009

Expected future benefit payments

2012	$	1,055
2013		1,125
2014		1,196
2015		1,218
2016		1,261
2017-2021		6,611