Employee Benefit Plans (Tables)

9 Months Ended

Sep. 30, 2011

Employee Benefit Plans [Abstract]

Components of net periodic pension and other post-retirement benefit cost

	Pension Benefits												Other Post-Retirement Benefits
	Three Months Ended September 30,						Nine Months Ended September 30,						Three Months Ended September 30,				Nine Months Ended September 30,
	2011			2010			2011			2010			2011		2010		2011		2010
Service cost	$	512		$	451		$	1,535		$	1,353		$	187	$	178	$	560	$	534
Interest cost		1,794			1,770			5,382			5,310			590		550		1,771		1,650
Expected return on plan assets		(1,947	)		(1,869	)		(5,843	)		(5,607	)		—		—		—		—
Amortization of prior service cost		100			131			301			393			303		303		910		910
Amortization of actuarial loss		1,004			702			3,013			2,104			—		—		—		—
Net periodic benefit cost	$	1,463		$	1,185		$	4,388		$	3,553		$	1,080	$	1,031	$	3,241	$	3,094