Benefit Plans and Other Postretirement Benefits (Tables)

9 Months Ended

Sep. 30, 2013

Benefit Plans and Other Postretirement Benefits

Schedule of components of net pension expense

	Pension Benefits						Other Postretirement Benefits
	Three months ended September 30,
	2013			2012			2013		2012
Service cost	$	2,103		$	1,911		$	40	$	45
Interest cost	5,117			5,387			127		169
Expected return on plan assets	(6,071		)	(6,089		)	—		—
Amortization of transition obligation	(27		)	(27		)	—		16
Amortization of prior service cost	485			535			—		—
Amortization of net actuarial losses	5,901			4,484			193		242
Net pension expense	$	7,508		$	6,201		$	360	$	472

	Pension Benefits						Other Postretirement Benefits
	Nine months ended September 30,
	2013			2012			2013		2012
Service cost	$	6,318		$	5,795		$	120	$	134
Interest cost	15,431			16,340			382		508
Expected return on plan assets	(18,346		)	(18,408		)	—		—
Amortization of transition obligation	(81		)	(81		)	—		47
Amortization of prior service cost	1,465			1,610			—		—
Amortization of net actuarial losses	17,703			13,592			578		725
Net pension expense	$	22,490		$	18,848		$	1,080	$	1,414