Investment in and Advances to Unconsolidated Affiliates Affiliate Balance Sheet (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015	Dec. 31, 2012
Investments in and Advances to Affiliates, Affiliate Balance Sheet [Abstract]
Current assets	$ 16.0	$ 24.5
Property and equipment, net	117.3	119.7
Other assets, net	107.0	106.6
Total assets	240.3	250.8
Current liabilities	13.5	21.6
Current portion of long-term debt	8.3	8.3
Long-term debt, excluding current portion	18.9	20.5	$ 50.0
Other liabilities	0.1	0.1
Members' equity	199.5	200.3
Total liabilities and members' equity	$ 240.3	$ 250.8