Income Taxes Components of net deferred tax assets (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Income taxes
Balance carryforwards, gross value	$ 899.6	$ 602.9
Deferred tax assets, future tax benefits	430.4	382.8
Deferred Tax Assets, Valuation Allowance	15.0	17.1
Charitable contribution
Income taxes
Charitable contributions, gross value	9.4	4.7
Deferred tax asset, charitable contribution	4.0	1.9
Deferred Tax Assets, Valuation Allowance	1.5	1.9
Domestic tax authority
Income taxes
Operating loss carryforwards, gross value	407.6	412.3
Tax credit carryforward, amount	0.0	0.0
Deferred tax assets, federal net operating loss	142.7	144.3
Deferred tax assets, tax credit carryforwards	241.1	207.8
Operating loss carryforwards, valuation allowance	0.0	0.0
Tax credit carryforward, valuation allowance	0.0	0.0
Foreign tax authority
Income taxes
Tax credit carryforward, amount	0.0	0.0
Deferred tax asset, federal foreign tax credit	13.5	15.2
Tax credit carryforward, valuation allowance	13.5	15.2
State and local jurisdiction
Income taxes
Operating loss carryforwards, gross value	482.6	185.9
Tax credit carryforward, amount	0.0	0.0
Deferred tax assets, tax credit carryforwards	4.8	4.3
Deferred tax asset, state net operating loss	24.3	9.3
Operating loss carryforwards, valuation allowance	0.0	0.0
Tax credit carryforward, valuation allowance	$ 0.0	$ 0.0