Income Taxes - Effective Tax Rate Reconciliation (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Effective income tax reconciliation, amount
Income Tax Expense at U.S. Statutory Rate		$ (125.8)	$ (46.4)	$ (74.4)
U.S. State and Local Tax (Expense) Benefit		(11.4)	(5.9)	(7.7)
Goodwill Related to Dispositions		0.0	(8.6)	0.0
Capital Loss on Subsidiary Stock		0.0	0.0	5.4
Permanent Items		1.7	(4.7)	(3.5)
Change in Valuation Allowance		1.8	(5.1)	(15.2)
International Tax Rate Differences		2.4	3.5	2.9
Foreign Withholding Tax		(0.2)	(0.1)	(0.4)
Non taxable Excise Tax Credit Refunds		0.0	0.0	29.4
Change in Tax Rates		1.0	4.5	(3.6)
U.S. Federal & State Research Credits	$ 20.1	5.5	20.1	0.0
Uncertain Tax Positions		(3.7)	(4.5)	0.0
Other		(1.7)	1.8	(0.3)
Income Tax (Expense) Benefit		$ (130.4)	$ (45.4)	$ (67.4)
Effective income tax reconciliation, percent
Income Tax Expense at U.S. Statutory Rate		35.00%	35.00%	35.00%
U.S. State and Local Tax (Expense) Benefit		3.20%	4.40%	3.60%
Goodwill Related to Dispositions		0.00%	6.50%	0.00%
Capital Loss on Subsidiary Stock		(0.00%)	(0.00%)	(2.60%)
Permanent Items		(0.50%)	3.50%	1.70%
Change in Valuation Allowance		(0.50%)	3.90%	7.20%
International Tax Rate Differences		(0.70%)	(2.60%)	(1.40%)
Foreign Withholding Tax		0.10%	0.00%	0.20%
Non taxable Excise Tax Credit Refunds		(0.00%)	(0.00%)	(13.80%)
Change in Tax Rates		(0.30%)	(3.40%)	1.70%
U.S. Federal & State Research Credits		(1.50%)	(15.10%)	(0.00%)
Uncertain Tax Positions		1.00%	3.40%	0.00%
Other		0.50%	(1.40%)	0.10%
Income Tax Expense, percent		36.30%	34.20%	31.70%