Recent Accounting Pronouncements Adoption of 2016-09 - Employee Share-Based Payment Transactions (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect on Retained Earnings, Net of Tax	$ (4.1)	$ 1.0
Adjustments for New Accounting Pronouncement [Member] | Previously Unrecognized Tax Benefits Due to NOL Carryforwards [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative Effect on Retained Earnings, Net of Tax		2.1
Adjustments for New Accounting Pronouncement [Member] | Forfeiture Rate Estimate Adjustment [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		$ 1.1