Employee Benefits (Tables)

6 Months Ended

Jun. 30, 2015

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 June 30,	2015			2014			2015		2014
Net periodic benefit cost
Service cost	$	1,669		$	1,303		$	1,305	$	924
Interest cost	1,500			1,468			713		586
Expected return on plan assets	(1,950		)	(1,739		)	—		—
Amortization of net loss	1,136			544			731		224
Net periodic benefit cost	$	2,355		$	1,576		$	2,749	$	1,734

	Pension Plan						Postretirement Benefit Plan
Six Months Ended June 30,	2015			2014			2015		2014
Net periodic benefit cost
Service cost	$	3,338		$	2,606		$	2,610	$	1,848
Interest cost	3,000			2,936			1,426		1,172
Expected return on plan assets	(3,900		)	(3,478		)	—		—
Amortization of net loss	2,272			1,088			1,462		448
Net periodic benefit cost	$	4,710		$	3,152		$	5,498	$	3,468