Employee and Retiree Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2014

Pension And Other Postretirement Benefits Disclosure [Line Items]

Amounts Included in Accumulated Other Comprehensive Income Not Recognized in Net Periodic Benefit Expense

(Thousands of dollars)	Pension Benefits		Other Postretirement Benefits
Net actuarial loss	$	(256,821)	(21,948)
Prior service (cost) credit		(2,456)	289
	$	(259,277)	(21,659)

Amounts Included in Accumulated Other Comprehensive Income Expected to be Amortization into Net Periodic Benefit Expense

(Thousands of dollars)	Pension Benefits		Other Postretirement Benefits
Net actuarial loss	$	(16,706)	(778)
Prior service (cost) credit		(854)	82
	$	(17,560)	(696)

Projected Benefit Obligations, Accumulated Benefit Obligations and Fair Value of Plan Assets for Plans where Accumulated Benefit Obligation Exceeded Fair Value of Plan Assets

	Projected Benefit Obligations			Accumulated Benefit Obligations		Fair Value of Plan Assets
(Thousands of dollars)	2014		2013	2014	2013	2014	2013
Funded qualified plans where    accumulated benefit obligation    exceeds fair value of plan assets	$	658,618	571,217	597,918	520,610	533,165	502,308
Unfunded nonqualified and directors'    plans where accumulated benefit    obligation exceeds fair value of    plan assets		147,018	115,492	127,200	102,198	–	–
Unfunded other postretirement plans		118,496	107,001	118,496	107,001	–	–

Components of Net Periodic Benefit Expense

	Pension Benefits				Other Postretirement Benefits
(Thousands of dollars)		2014	2013	2012	2014	2013	2012
Service cost	$	22,470	26,346	23,500	2,459	4,566	3,958
Interest cost		33,680	30,903	29,869	4,617	5,189	5,174
Expected return on plan assets		(33,723)	(28,974)	(25,826)	–	–	–
Amortization of prior service     cost (credit)		899	1,006	1,254	(82)	(143)	(173)
Amortization of transitional    (asset) liability		(480)	(514)	(529)	–	8	8
Recognized actuarial loss		9,471	17,338	16,389	5	1,484	1,317
		32,317	46,105	44,657	6,999	11,104	10,284
Termination benefits expense		–	849	6,177	–	–	–
Curtailment expense (benefit)		–	1,365	–	–	(442)	–
Net periodic benefit expense	$	32,317	48,319	50,834	6,999	10,662	10,284

Weighted-Average Assumptions used in Measurement of Benefit Obligations and Net Periodic Benefit Expense

	Benefit Obligations				Net Periodic Benefit Expense
	Pension Benefits		Other Postretirement Benefits		Pension Benefits		Other Postretirement Benefits
	December 31		December 31		Year		Year
	2014	2013	2014	2013	2014	2013	2014	2013
Discount rate	3.94%	4.78%	4.12%	4.91%	4.56%	4.23%	4.91%	4.18%
Expected return on plan assets	6.11%	6.24%	–	–	6.11%	6.24%	–	–
Rate of compensation increase	3.69%	4.14%	–	–	3.69%	4.12%	–	–

Benefit Payments Reflecting Expected Future Service as Appropriate which are Expected to be Paid in Future Years from Assets of Plans or by Company

(Thousands of dollars)	Pension Benefits		Other Postretirement Benefits
2015	$	33,516	6,349
2016		34,212	6,573
2017		35,144	6,730
2018		36,439	6,943
2019		37,671	7,225
2020-2024		208,294	40,535

One Percent Change in Assumed Health Care Cost Trend Rates

(Thousands of dollars)	1% Increase		1% Decrease
Effect on total service and interest cost components of net periodic postretirement     benefit expense for the year ended December 31, 2014	$	1,190	(942)
Effect on the health care component of the accumulated postretirement benefit     obligation at December 31, 2014		17,879	(14,456)

Effects of Fair Value Measurements Using Significant Unobservable Inputs on Changes in Level 3 Plan Assets

(Thousands of dollars)	Hedged Funds and Other Alternative Strategies
Total at December 31, 2012		$	14,654
Actual return on plan assets:
Relating to assets held at the reporting date			3,134
Relating to assets sold during the period			–
Purchases, sales and settlements			15,000
Total at December 31, 2013			32,788
Actual return on plan assets:
Relating to assets held at the reporting date			1,164
Relating to assets sold during the period			–
Purchases, sales and settlements			–
Total at December 31, 2014		$	33,952

Domestic Plans [Member]

Pension And Other Postretirement Benefits Disclosure [Line Items]

Plans' Benefit Obligations and Fair Value of Assets and Statement of Funded Status

	Pension Benefits			Other Postretirement Benefits
(Thousands of dollars)	2014		2013	2014	2013
Change in benefit obligation
Obligation at January 1	$	707,254	721,531	107,001	124,134
Service cost		22,470	26,346	2,459	4,566
Interest cost		33,680	30,903	4,617	5,189
Plan amendments		–	1,989	–	–
Participant contributions		5	21	1,406	1,376
Actuarial loss (gain)		122,824	(9,876)	8,150	(8,324)
Medicare Part D subsidy		–	–	404	384
Exchange rate changes		(14,614)	1,852	(55)	(36)
Benefits paid		(35,044)	(38,745)	(5,486)	(5,211)
Special termination benefits		–	849	–	–
Curtailments		(11,023)	(26,463)	–	(15,077)
Obligation assumed by MUSA at separation		–	(1,153)	–	–
Obligation at December 31		825,552	707,254	118,496	107,001
Change in plan assets
Fair value of plan assets at January 1		533,108	463,546	–	–
Actual return on plan assets		31,340	61,932	–	–
Employer contributions		47,279	46,726	3,676	3,451
Participant contributions		5	21	1,406	1,376
Medicare Part D subsidy		–	–	404	384
Exchange rate changes		(13,284)	1,594	–	–
Benefits paid		(35,044)	(38,745)	(5,486)	(5,211)
Other		(2,426)	(1,966)	–	–
Fair value of plan assets at December 31		560,978	533,108	–	–
Funded status and amounts recognized in the     Consolidated Balance Sheets at December 31
Deferred charges and other assets		7,899	10,254	–	–
Other accrued liabilities		(5,996)	(5,565)	(5,515)	(5,920)
Deferred credits and other liabilities		(252,237)	(158,589)	(112,981)	(101,081)
Liabilities associated with assets held for sale		(14,240)	(20,246)	–	–
Funded status and net plan liability recognized             at December 31	$	(264,574)	(174,146)	(118,496)	(107,001)

Foreign Plans [Member]

Pension And Other Postretirement Benefits Disclosure [Line Items]

Plans' Benefit Obligations and Fair Value of Assets and Statement of Funded Status

	Pension Benefits			Other Postretirement Benefits
(Thousands of dollars)	2014		2013	2014	2013
Benefit obligation at December 31	$	222,497	211,799	648	541
Fair value of plan assets at December 31		202,305	188,575	–	–
Net plan liabilities recognized		20,192	23,224	648	541
Net periodic benefit expense		12,968	12,622	152	92

Other Postretirement Benefits [Member]

Pension And Other Postretirement Benefits Disclosure [Line Items]

Asset Allocation for Benefit Plans

At December 31, 2014, the fair value measurements of retirement plan assets within the fair value hierarchy are included in the table that follows.

			Fair Value Measurements Using
(Thousands of dollars)	Fair Value at December 31, 2014		Quoted Prices in Active Markets for Identical Assets (Level 1)	Significant Other Observable Inputs (Level 2)	Significant Unobservable Inputs (Level 3)
Domestic Plans
Equity securities:
U.S. core equity	$	67,863	67,863	–	–
U.S. small/midcap		33,709	33,709	–	–
Hedged funds and other          alternative strategies		52,905	–	18,953	33,952
International commingled          trust fund		75,702	–	75,702	–
Emerging market commingled         equity fund		19,908	–	19,908	–
Fixed income securities:
U.S. fixed income		80,577	–	80,577	–
International commingled          trust fund		17,559	–	17,559	–
Emerging market mutual fund		8,069	–	8,069	–
Cash and equivalents		2,381	2,381	–	–
Total Domestic Plans		358,673	103,953	220,768	33,952
Foreign Plans
Equity securities funds		106,694	–	106,694	–
Fixed income securities funds		66,435	–	66,435	–
Diversified pooled fund		27,813	–	27,813	–
Cash and equivalents		1,363	1,363	–	–
Total Foreign Plans		202,305	1,363	200,942	–
Total	$	560,978	105,316	421,710	33,952

At December 31, 2013, the fair value measurements of retirement plan assets within the fair value hierarchy are included in the table that follows.

			Fair Value Measurements Using
(Thousands of dollars)	Fair Value at December 31, 2013		Quoted Prices in Active Markets for Identical Assets (Level 1)	Significant Other Observable Inputs (Level 2)	Significant Unobservable Inputs (Level 3)
Domestic Plans
Equity securities:
U.S. core equity	$	89,255	89,255	–	–
U.S. small/midcap		37,149	37,149	–	–
Hedged funds and other          alternative strategies		32,788	–	–	32,788
International commingled          trust fund		77,041	–	77,041	–
Emerging market commingled         equity fund		9,654	–	9,654	–
Fixed income securities:
U.S. fixed income		72,240	–	72,240	–
International commingled          trust fund		14,865	–	14,865	–
Emerging market mutual fund		8,549	–	8,549	–
Cash and equivalents		2,992	2,992	–	–
Total Domestic Plans		344,533	129,396	182,349	32,788
Foreign Plans
Equity securities funds		99,085	–	99,085	–
Fixed income securities funds		57,030	–	57,030	–
Diversified pooled fund		30,800	–	30,800	–
Cash and equivalents		1,660	1,660	–	–
Total Foreign Plans		188,575	1,660	186,915	–
Total	$	533,108	131,056	369,264	32,788

Funded Defined Benefit Pension Plans [Member]

Pension And Other Postretirement Benefits Disclosure [Line Items]

Asset Allocation for Benefit Plans

	December 31,
	2014		2013
Equity securities	66.6	%	68.4	%
Fixed income securities	32.5		30.7
Cash equivalents	0.9		0.9
	100.0	%	100.0	%