Description of Business and Accounting Policies (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Jan. 01, 2019	Dec. 31, 2018
Description of Business and Accounting Policies [Line Items]
Accounts Receivable from one customer greater than 10%, percentage	10.00%
Number of customers, exceeds 10% of total accounts receivable	0
Percentage of Revenue by Foreign Subsidiaries	5.00%	6.00%
Operating Lease, Right-of-Use Asset	$ 37.2		$ 38.3	$ 0.0
Operating Lease, Liability	$ 44.3		$ 46.2
Verizon Communications Inc. [Member]
Description of Business and Accounting Policies [Line Items]
Accounts Receivable from one customer greater than 10%, percentage				18.00%