Significant Accounting Policies Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		35.00%	35.00%	35.00%
Tax Cuts and Jobs Act of 2017 Incomplete Accounting Change In Tax Rate Deferred Tax Liability Provisional Income Tax (Expense) Benefit		$ 394.0
Tax Cuts And Jobs Act of 2017 Incomplete Accounting Transition Tax For Accumulated Foreign Earnings Provisional Income Tax Expense (Benefit)		22.0
Undistributed Earnings of Foreign Subsidiaries		$ 237.9
Scenario, Forecast [Member]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%