Employee Benefits (Tables)

9 Months Ended

Sep. 30, 2017

Retirement Benefits [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 September 30,	2017			2016			2017			2016
Net periodic benefit cost
Service cost	$	1,714		$	1,623		$	505		$	932
Interest cost	1,765			1,663			482			754
Expected return on plan assets	(2,413		)	(1,988		)	—			—
Amortization of prior service credit	—			—			(1,352		)	—
Amortization of net loss	891			992			462			379
Net periodic benefit cost	$	1,957		$	2,290		$	97		$	2,065

	Pension Plan						Postretirement Benefit Plan
Nine Months Ended September 30,	2017			2016			2017			2016
Net periodic benefit cost
Service cost	$	5,141		$	4,869		$	1,515		$	2,796
Interest cost	5,295			4,989			1,446			2,262
Expected return on plan assets	(7,237		)	(5,964		)	—			—
Amortization of prior service credit	—			—			(4,056		)	—
Amortization of net loss	2,673			2,976			1,384			1,137
Net periodic benefit cost	$	5,872		$	6,870		$	289		$	6,195