Income and Partnership Taxes Narrative (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Unrecognized Tax Benefits, Interest on Income Taxes Accrued	$ 300,000
Provision (benefit) for taxes	31,757,000	7,877,000	2,670,000
Provision for the PTP tax	8,700,000	8,300,000	7,900,000
Provision (benefit) pertaining to corporate subsidiaries	23,012,000	(411,000)	(5,249,000)
U.S. federal statutory income tax rate	35.00%
Foreign tax credit carryforwards available for U.S. federal income tax purposes	31,162,000	40,439,000
Change in deferred tax asset valuation allowance in 2011	6,100,000
Deferred tax assets, valuation allowance	11,253,000	17,283,000
Tax attribute carryforwards	10,948,000	20,209,000
Alternative minimum tax credits	800,000
General business credits	4,800,000
State net operating loss carryforwards	5,300,000
Deferred tax assets, other comprehensive income (loss)	2,200,000
Deferred Tax Liabilities, Other Comprehensive Income		2,600,000
Unrecognized Tax Benefits, Income Tax Penalties Accrued	200,000
Unrecognized Tax Benefits, Increases Resulting from Current Period Tax Positions	1,100,000
Unrecognized Tax Benefits	$ 1,100,000	$ 0