Supplemental Cash Flow Information - Reconciliation of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016		Jun. 30, 2016	[2]	Dec. 31, 2015	[2]
Supplemental Cash Flow Elements [Abstract]
Cash and cash equivalents	$ 571.1	$ 370.6
Restricted cash	19.1	30.5	[1]
Total cash, cash equivalents and restricted cash shown in the consolidated statements of cash flows	$ 590.2	$ 401.1		$ 493.8		$ 396.8

[1] Amounts were changed to conform to the current-year presentation. See Note 11.

[2] Amounts were changed to conform to the current-year presentation. See Note 11.