CONSOLIDATED STATEMENTS OF PARTNERS' CAPITAL (USD $) In Millions, unless otherwise specified	Total	General Partner's Interest	Common Units	Class B Common Units
Partners' capital at Dec. 31, 2011	$ 269.3	$ 33.4	$ 234.8	$ 1.1
Increase (Decrease) in Partners' Capital
Net earnings	124.2	53.1	69.9	1.2
Distributions	(151.2)	(65.9)	(83.9)	(1.4)
Partners' capital at Mar. 31, 2012	242.3	20.6	220.8	0.9
Partners' capital at Dec. 31, 2012	271.8	32.3	238.3	1.2
Increase (Decrease) in Partners' Capital
Net earnings	166.8	73.0	92.2	1.6
Distributions	(118.0)	(49.5)	(67.3)	(1.2)
Partners' capital at Mar. 31, 2013	$ 320.6	$ 55.8	$ 263.2	$ 1.6