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-Paragraph 2
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No definition available.

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Share-Based Compensation - Restricted Stock Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award
Fair value of restricted stocks granted	$ 5.9	$ 59.4	$ 20.7
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award
Fair value of restricted stocks granted	$ 37.7	$ 36.9	$ 28.0
Restricted stocks available for future grant under the Company's option plans (in shares)	900,000.0
Restricted Stock \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award
Vesting period of restricted stocks	3 years
Restricted Stock \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award
Vesting period of restricted stocks	4 years