Changes in Stockholders' Equity (Changes in Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated derivative net losses as of beginning of period	$ 2,837.2
Net losses reclassified from accumulated other comprehensive loss	4.2	$ 2.4
Other comprehensive income, net of reclassification adjustments	48.9	94.3
Accumulated derivative net losses as of end of period	2,876.0
Defined Benefit Pension Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated derivative net losses as of beginning of period	(304.5)
Other comprehensive income before reclassifications	0.0
Net losses reclassified from accumulated other comprehensive loss	2.9	$ 2.2
Other comprehensive income, net of reclassification adjustments	2.9
Accumulated derivative net losses as of end of period	(301.6)
Deferred Net (Losses) Gains on Derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated derivative net losses as of beginning of period	(8.7)
Other comprehensive income before reclassifications	2.0
Net losses reclassified from accumulated other comprehensive loss	1.3
Other comprehensive income, net of reclassification adjustments	3.3
Accumulated derivative net losses as of end of period	(5.4)
Cumulative Translatoin Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated derivative net losses as of beginning of period	(1,128.4)
Other comprehensive income before reclassifications	41.1
Net losses reclassified from accumulated other comprehensive loss	0.0
Other comprehensive income, net of reclassification adjustments	41.1
Accumulated derivative net losses as of end of period	(1,087.3)
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated derivative net losses as of beginning of period	(1,441.6)
Other comprehensive income before reclassifications	43.1
Net losses reclassified from accumulated other comprehensive loss	4.2
Other comprehensive income, net of reclassification adjustments	47.3
Accumulated derivative net losses as of end of period	$ (1,394.3)