Stock-Based Compensation, Stock-based Comp Expense (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Stock-Based Compensation
Expense incurred for stock-based compensation plans	$ 14.4	$ 12.7
Recognized tax benefit related to stock-based compensation	8.6	5.9
Excess tax benefit from option exercises	$ 6.8	$ 4.1

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
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- References

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- Definition

The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Amount of tax benefit from exercise of stock options granted under share-based compensation arrangement.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
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