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Revenue Recognition - Change in Contract Liabilities (Details) - USD ($)
$ in Millions
3 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Revenue from Contract with Customer [Abstract]    
Balance, beginning $ 227.4 $ 215.8
Revenue recognized (12.8) (14.9)
Revenue deferred 15.6 18.2
Acquired liabilities 0.0 0.1
Balance, ending $ 230.2 $ 219.2