Revenue Recognition and Related Costs (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Trade receivables, allowance for doubtful accounts	$ 63.6		$ 63.6		$ 48.3
Contract assets	31.4		31.4		43.3
Deferred revenue	331.7		331.7		437.3
Revenue recognized			292.8
Aggregate assets associated with incremental costs to obtain a contract and contract fulfillment costs	54.1		54.1		$ 34.8
Amortization related to contract costs	$ 4.9	$ 26.4	$ 76.7	$ 80.3
Performance obligation period			Revenue from customers who are subject to contracts is generally recognized over the term of such contracts, which is typically 12 months for our residential service contracts, one to three years for our mobile service contracts and one to five years