Share-Based Payments (Details 11) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Shares issued under ESPP	6,200,000
2015 ESPP
Employee Stock Ownership Plan (ESOP) Disclosures [Line Items]
Shares issued under ESPP	170,000	167,000	190,000
Cash received under ESPP	$ 40.5	$ 39.8	$ 41.5

Aggregate change in value for stock issued during the period as a result of employee stock purchase plan.

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