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Income Taxes - Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions | Dec. 31, 2017 | Dec. 31, 2016
--- | --- | ---
Deferred Tax Assets |  |
State net operating loss carryforwards | $ 16.8 | $ 17.4
Foreign loss carryforwards | 16.3 | 14.6
Tax benefit of uncertain tax positions | 11.4 | 12.1
Deferred compensation | 10.4 | 34.1
Foreign tax credits | 0.0 | 10.0
Accrued expenses | 1.3 | 3.9
Total deferred tax assets | 56.2 | 92.1
Valuation allowance | (24.1) | (22.1)
Deferred tax assets, net of valuation allowance | 32.1 | 70.0
Deferred Tax Liabilities |  |
Intangible asset amortization | (258.6) | (396.8)
Non-deductible intangible amortization | (150.8) | (177.0)
Convertible securities interest | (77.9) | (109.0)
Deferred income | (5.9) | (47.2)
Other | (6.3) | (0.8)
Total deferred tax liabilities | (499.5) | (730.8)
Deferred income tax liability (net) | $ (467.4) | $ (660.8)

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