Significant Accounting Policies - Goodwill, Other Intangible and Long-Lived Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Acquired Finite-Lived Intangible Assets [Line Items]
Impairment of Intangible Assets (Excluding Goodwill)		$ 0.3	$ 0.2
Customer and advertiser relationships | Minimum
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated useful life of definite-lived intangible asset	5 years
Customer and advertiser relationships | Maximum
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated useful life of definite-lived intangible asset	10 years
Patents and developed technology | Minimum
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated useful life of definite-lived intangible asset	2 years
Patents and developed technology | Maximum
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated useful life of definite-lived intangible asset	20 years
Media content | Minimum
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated useful life of definite-lived intangible asset	5 years
Media content | Maximum
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated useful life of definite-lived intangible asset	10 years
Trademarks and trade names | Minimum
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated useful life of definite-lived intangible asset	1 year
Trademarks and trade names | Maximum
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated useful life of definite-lived intangible asset	13 years
Service contracts and other
Acquired Finite-Lived Intangible Assets [Line Items]
Estimated useful life of definite-lived intangible asset	10 years