Interest And Other Income (Components Of Interest And Other Income) (Details) (USD $)	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Interest and Other Income [Abstract]
Alaskan Petroleum Production Tax credits and refunds	$ 19,408,000	[1]	$ 11,846,000	[1]
Equity interest in income of unconsolidated affiliate	3,536,000		441,000
Other income	1,876,000		1,641,000
Deferred compensation plan income	1,627,000		1,374,000
Interest income	93,000		57,000
Third-party income from vertical integration services	(7,225,000)	[2]	6,549,000	[2]
Total interest and other income	19,315,000		21,908,000
GrossRevenuesIncludedInThirdPartyIncomeFromVerticalIntegrationServices	56,100,000		75,400,000
GrossExpensesIncludedInThirdPartyIncomeFromVerticalIntegrationServices	$ 63,300,000		$ 68,900,000

[1] The Company earns Alaskan Petroleum Production Tax ("PPT") credits on qualifying capital expenditures. The Company recognizes income from PPT credits when they are realized through cash refunds or as reductions in production and ad valorem taxes if realizable as offsets to PPT expense.

[2] Income (loss) from vertical integration services represent net margins that result from Company-provided fracture stimulation, drilling and related service operations, which are ancillary to and supportive of the Company's oil and gas joint operating activities, and do not represent intercompany transactions. For the three months ended March 31, 2013 and 2012, these net margins include $56.1 million and $75.4 million of gross vertical integration revenues, respectively, and $63.3 million and $68.9 million of total vertical integration costs and expenses, respectively.