Net Earnings per Common Unit (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Basic earnings per Common Unit:
Net earnings	$ 79.2	$ 69.4	$ 99.3	$ 59.0	$ 95.0	$ 72.0	$ 100.1	$ 102.9	$ 306.9	$ 370.0	$ 502.4
Weighted-average Common Units outstanding									18,500,000	18,500,000	18,500,000
Net earnings per Common Unit	$ 2.49	$ 2.23	$ 3.31	$ 2.03	$ 3.05	$ 2.60	$ 3.16	$ 3.26	$ 10.06	$ 12.07	$ 15.77
Dilutive TNCLP units outstanding									0		0