Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2011

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of taxes other than income taxes

Collections and payments of excise taxes are reported on a gross basis. These amounts are included in taxes other than income taxes on the consolidated statements of income as follows:

Years ended December 31, (in thousands)	2011		2010		2009
Taxes on revenues	$	25,268	$	30,704	$	31,704