Indebtedness - Overview (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Debt Disclosure [Abstract]
Debt, Weighted Average Interest Rate	4.60%	5.00%	5.10%
Interest Costs, Capitalized During Period	$ 16.7	$ 13.2	$ 9.6
Cash paid for interest	$ 149.6	$ 164.9	$ 143.2