Benefit Plans and Other Postretirement Benefits (Tables)

9 Months Ended

Sep. 30, 2013

Compensation and Retirement Disclosure [Abstract]

Components of Net Periodic Benefit Cost

Components of Net Periodic Benefit Cost

	Three Months Ended Sept. 30
	2013			2012			2013			2012
(Thousands of Dollars)	Pension Benefits						Postretirement Health Care Benefits
Service cost	$	1,421		$	1,142		$	6		$	5
Interest cost	1,731			1,918			190			268
Expected return on plan assets	(2,499		)	(2,622		)	(11		)	(13		)
Amortization of transition obligation	—			—			—			42
Amortization of prior service cost (credit)	104			442			(88		)	(4		)
Amortization of net loss	1,981			1,460			241			123
Net benefit cost recognized for financial reporting	$	2,738		$	2,340		$	338		$	421

	Nine Months Ended Sept. 30
	2013			2012			2013			2012
(Thousands of Dollars)	Pension Benefits						Postretirement Health Care Benefits
Service cost	$	4,262		$	3,426		$	18		$	15
Interest cost	5,193			5,753			570			806
Expected return on plan assets	(7,496		)	(7,867		)	(32		)	(38		)
Amortization of transition obligation	—			—			—			128
Amortization of prior service cost (credit)	312			1,328			(264		)	(11		)
Amortization of net loss	5,943			4,382			723			365
Net benefit cost recognized for financial reporting	$	8,214		$	7,022		$	1,015		$	1,265