Lease Obligations (Schedule of Future Lease Commitments) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Capital Leases
Future minimum lease commitments, 2017	$ 50.9
Future minimum lease commitments, 2018	33.6
Future minimum lease commitments, 2019	12.9
Future minimum lease commitments, 2020	3.8
Future minimum lease commitments, 2021	2.1
Future minimum lease commitments, thereafter	0.0
Total minimum lease payments	103.3
Less amounts representing interest	(4.7)
Total capital lease obligations, net of interest	98.6	$ 130.9
Less current portion	(48.6)
Long-term portion of capital lease obligations, net of interest	50.0
Operating Leases
Future minimum lease commitments, 2017	93.8
Future minimum lease commitments, 2018	75.4
Future minimum lease commitments, 2019	47.4
Future minimum lease commitments, 2020	27.1
Future minimum lease commitments, 2021	13.7
Future minimum lease commitments, thereafter	33.9
Total minimum lease payments	$ 291.3