Description of Business and Accounting Policies (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016	Oct. 05, 2016	Oct. 04, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of customers, exceeds 10% of total accounts receivable	1
Accounts Receivable from one customer greater than 10%, percentage	18.00%		21.00%
Revenue from one customer greater than 10%, percentage		11.00%
Common Stock, Shares, Issued	42,133,326		42,056,237	42,055,001	210,275,005
Total Par Value, Amount, Reclassified				$ 1.7
Business Combination, Consideration Transferred	$ 10.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	0.4
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill	1.2
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Working Capital	4.1
Goodwill, Acquired During Period	$ 4.3
Available-for-Sale Securities, Shares Sold	2,800,000
Proceeds from sale of Investment in CyrusOne	$ 140.7	$ 0.0
Gain on sale of Investment in CyrusOne	117.7	$ 0.0
AMT refundable tax credits reclassified	$ 3.4		$ 14.5