Employee Benefits (Tables)

3 Months Ended

Mar. 31, 2013

Compensation and Retirement Disclosure [Abstract]

Net Periodic Benefit Cost

The components of the net periodic benefit cost for our pension and postretirement benefit plans are as follows:

	Pension Plan						Postretirement Benefit Plan
Three Months Ended March 31,	2013			2012			2013		2012
Net periodic benefit cost
Service cost	$	1,282		$	791		$	753	$	496
Interest cost	1,262			1,190			424		398
Expected return on plan assets	(1,336		)	(1,322		)	—		—
Amortization of prior service cost	—			3			—		(8		)
Amortization of net loss	1,106			592			136		56
Net periodic benefit cost	$	2,314		$	1,254		$	1,313	$	942