Redeemable Noncontrolling Interests - Table 1 (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Redeemable Noncontrolling Interest [Line Items]
Balance at beginning of period	$ 84.7
Net Income attributable to noncontrolling interest	13.8	$ 6.6	$ 5.8
Distributions declared	(49.0)	(44.9)	(40.4)
Balance at end of period	121.1	84.7
Altoona and Jonesboro [Member]
Redeemable Noncontrolling Interest [Line Items]
Balance at beginning of period		13.5
Net Income attributable to noncontrolling interest	13.8	6.6	5.8
Distributions declared	(7.3)	(8.5)	(4.9)
Contribution to joint venture	0.0	4.3	7.1
Change in fair value		4.3	(1.7)
Balance at end of period	121.1		13.5
Altoona [Member]
Redeemable Noncontrolling Interest [Line Items]
Balance at beginning of period		13.5	7.2
Balance at end of period			13.5
Altoona, Jonesboro, and Encompass [Member]
Redeemable Noncontrolling Interest [Line Items]
Balance at beginning of period	84.7
Change in fair value	29.9
Balance at end of period		84.7
Encompass [Member]
Redeemable Noncontrolling Interest [Line Items]
Redeemable noncontrolling interests, Increase from acquisition	$ 0.0	$ 64.5	$ 0.0