Net Earnings per Common Unit (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Basic earnings per Common Unit:
Net earnings	$ 100.1	$ 149.3	$ 203.0	$ 316.1
Net earnings allocable to General Partner	40.7	63.8	82.2	136.8
Weighted average units outstanding	18.5	18.5	18.5	18.5
Net earnings per Common Unit (in dollars per unit)	$ 3.16	$ 4.54	$ 6.42	$ 9.52
Dilutive TNCLP units outstanding	0	0	0	0
Class B Common Units
Basic earnings per Common Unit:
Net earnings allocable	1.0	1.5	2.0	3.1
Common Units
Basic earnings per Common Unit:
Net earnings allocable	$ 58.4	$ 84.0	$ 118.8	$ 176.2