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2. Acquisitions (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
2. Acquisitions (Details) - USD ($) $ in Millions	Sep. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2019	Aug. 02, 2019	Mar. 04, 2019
Business Combinations [Abstract]
Business Combination, Consideration Transferred	$ 60.0	$ 20.0
Payments to Acquire Businesses, Net of Cash Acquired	59.7	16.0	$ 4.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles					$ 26.8	$ 5.5
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net					$ 4.2
Goodwill, Acquired During Period	$ 28.7	15.6		$ 44.3
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill						$ 0.2
Business Combination, Consideration Transferred, Liabilities Incurred		$ 1.3