Reconciliation of Plans' Benefit Obligations and Fair Value of Assets and Statement of Funded Status (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Change in plan assets
Fair value of plan assets, Ending Balance	$ 463,546,000	$ 404,350,000
Pension Benefits
Change in benefit obligation
Obligations, Beginning Balance	629,568,000	575,300,000
Service cost	23,500,000	22,406,000	20,706,000
Interest cost	29,869,000	30,785,000	30,144,000
Plan amendments	0	483,000
Participant contributions	30,000	35,000
Actuarial loss	55,479,000	66,010,000
Medicare Part D subsidy	0	0
Exchange rate changes	7,125,000	(2,109,000)
Benefits paid	(30,217,000)	(27,745,000)
Reduction due to sale of the Superior refinery	0	(23,021,000)
Special termination benefits	6,177,000	695,000
Curtailments	0	(13,271,000)
Obligations, Ending Balance	721,531,000	629,568,000	575,300,000
Change in plan assets
Fair value of plan assets, Beginning Balance	404,350,000	416,272,000
Actual return on plan assets	41,674,000	(1,415,000)
Employer contributions	42,207,000	38,357,000
Participant contributions	30,000	35,000
Medicare Part D subsidy	0	0
Exchange rate changes	6,289,000	(1,786,000)
Benefits paid	(30,217,000)	(27,745,000)
Distribution to acquirer of the Superior refinery	0	(18,720,000)
Other	(787,000)	(648,000)
Fair value of plan assets, Ending Balance	463,546,000	404,350,000	416,272,000
Funded status and amounts recognized in the Consolidated Balance Sheets at December 31
Deferred charges and other assets	9,679,000	10,621,000
Other accrued liabilities	(5,556,000)	(3,488,000)
Deferred credits and other liabilities	(262,108,000)	(232,351,000)
Funded status and net plan liability recognized at the end of the period	(257,985,000)	(225,218,000)
Other Postretirement Benefits
Change in benefit obligation
Obligations, Beginning Balance	114,962,000	122,879,000
Service cost	3,958,000	4,547,000	4,133,000
Interest cost	5,174,000	6,141,000	6,211,000
Plan amendments	0	0
Participant contributions	1,035,000	1,049,000
Actuarial loss	4,686,000	4,791,000
Medicare Part D subsidy	432,000	555,000
Exchange rate changes	14,000	(11,000)
Benefits paid	(6,127,000)	(5,667,000)
Reduction due to sale of the Superior refinery	0	0
Special termination benefits	0	0
Curtailments	0	(19,322,000)
Obligations, Ending Balance	124,134,000	114,962,000	122,879,000
Change in plan assets
Fair value of plan assets, Beginning Balance	0	0
Actual return on plan assets	0	0
Employer contributions	4,660,000	4,063,000
Participant contributions	1,035,000	1,049,000
Medicare Part D subsidy	432,000	555,000
Exchange rate changes	0	0
Benefits paid	(6,127,000)	(5,667,000)
Distribution to acquirer of the Superior refinery	0	0
Other	0	0
Fair value of plan assets, Ending Balance	0	0	0
Funded status and amounts recognized in the Consolidated Balance Sheets at December 31
Deferred charges and other assets	0	0
Other accrued liabilities	(5,646,000)	(5,022,000)
Deferred credits and other liabilities	(118,488,000)	(109,940,000)
Funded status and net plan liability recognized at the end of the period	$ (124,134,000)	$ (114,962,000)