Net Earnings per Common Unit (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Basic earnings per common unit:
Net earnings	$ 72.7	$ 131.8	$ 388.8	$ 410.8
Net earnings allocable to General Partner	(25.4)	(56.6)	(162.2)	(176.5)
Weighted average units outstanding	18.5	18.5	18.5	18.5
Net earnings per common unit (in dollars per unit)	$ 2.52	$ 4.00	$ 12.04	$ 12.45
Dilutive TNCLP units outstanding			0	0
Class B Common Units
Basic earnings per common unit:
Net earnings allocated	0.7	1.3	3.8	4.0
Common Units
Basic earnings per common unit:
Net earnings allocated	$ 46.6	$ 73.9	$ 222.8	$ 230.3