Benefit Plans (Tables)

9 Months Ended

Sep. 30, 2011

Benefit Plans [Abstract]

Components of Net Periodic Benefit Cost

	Three Months Ended September 30,
	Pension Benefits						Other Benefits
	2011			2010			2011			2010
Components of net periodic benefit cost
Service cost	$	2,713		$	2,500		$	—		$	—
Interest cost		7,873			7,680			233			249
Expected return on plan assets		(10,183	)		(9,604	)		—			—
Amortization of prior service cost		65			48			(130	)		(130	)
Recognized net actuarial loss		2,349			1,512			98			71
Net periodic pension benefit cost	$	2,817		$	2,136		$	201		$	190
	Nine Months Ended September 30,
	Pension Benefits						Other Benefits
	2011			2010			2011			2010
Components of net periodic benefit cost
Service cost	$	8,139		$	7,498		$	—		$	—
Interest cost		23,617			23,042			698			745
Expected return on plan assets		(30,550	)		(28,810	)		—			—
Amortization of prior service cost		194			145			(388	)		(388	)
Recognized net actuarial loss		7,149			4,229			292			213
Net periodic pension benefit cost	$	8,549		$	6,104		$	602		$	570