Income Taxes (Details Textual) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Contingency [Line Items]
Income from continuing operations before income taxes for U.S. operations	$ 1,051.4	$ 571.2	$ 376.3
Income from continuing operations before income taxes for foreign operations	12.6	19.3	9.6
Tax benefit from reversal of valuation allowance on foreign tax credits		6.4
Adjustment to net deferred tax liability for state tax filing responsibilities		5.1
Tax benefit from final audit settlement with IRS			3.5
Tax benefit recognized on release of net state tax reserves			4.4
Additions for tax positions of prior years	2.5	2.8	0
Reduction in tax positions of prior years	0.1	0	1.1
Unrecognized tax benefits including interest and penalties that would affect the Company's effective tax rate if recognized	15.0	13.8
Total accrued interest and penalties related to uncertain tax positions	11.6	10.8
Increase (decrease) in income tax expense related to interest and penalties on unrecognized tax benefits	0.8	0.5	(3.0)
Lapse in Statute of Limitations
Income Tax Contingency [Line Items]
Reasonably possible decrease to unrecognized tax benefits within twelve months	0.1
Swiss subsidiary
Income Tax Contingency [Line Items]
Number of subsidiaries	2
General period of statute of limitations in Switzerland	5 years
Extended period of statute of limitations in Switzerland	15 years
U.S. Federal
Income Tax Contingency [Line Items]
Net operating loss carryforwards	33.5
State and local
Income Tax Contingency [Line Items]
Net operating loss carryforwards	$ 3.6