Redeemable Noncontrolling Interests - Table 1 (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Redeemable Noncontrolling Interest [Line Items]
Balance at beginning of period	$ 7.2
Net Income attributable to noncontrolling interest	5.8	3.8	3.6
Distributions declared	(40.4)	(45.4)	(40.5)
Balance at end of period	13.5	7.2
Altoona and Jonesboro [Member]
Redeemable Noncontrolling Interest [Line Items]
Net Income attributable to noncontrolling interest	5.8
Distributions declared	(4.9)
Contribution to joint venture	7.1
Change in fair value	(1.7)
Balance at end of period	13.5
Altoona [Member]
Redeemable Noncontrolling Interest [Line Items]
Balance at beginning of period		7.3	7.2
Net Income attributable to noncontrolling interest		3.8	3.6
Distributions declared		(3.9)	(3.5)
Contribution to joint venture		0	0
Change in fair value		0	0
Balance at end of period		$ 7.2	$ 7.3