Segment Reporting Total Assets (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Segment Reporting
Total assets	$ 30,184.5	$ 30,246.9
UNITED STATES
Segment Reporting
Total assets	19,319.4	19,353.6
Canada [Member]
Segment Reporting
Total assets	4,688.5	4,835.7
Europe [Member]
Segment Reporting
Total assets	5,691.6	5,522.0
International [Member]
Segment Reporting
Total assets	275.6	294.8
Corporate [Member]
Segment Reporting
Total assets	$ 209.4	$ 240.8