Fair Value of Financial Instruments (Nonrecurring) (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Apr. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property and equipment, net		$ 449,199	$ 375,654
Capitalized data and database developement costs net		327,921	327,841
Goodwill		2,107,255	1,881,547	$ 1,780,758
Investment in affiliates, net		40,809	69,205
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property and equipment, net		0	0	0
Capitalized data and database developement costs net		0
Goodwill				0
Investment in affiliates, net		5,662		0
Non-financial instruments		5,662		0
Total Losses, non-financial instruments		26,318		5,330
Fair Value, Measurements, Nonrecurring [Member] | Property and equipment, net [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Losses, non-financial instruments		2,005	3,770	1,070
Fair Value, Measurements, Nonrecurring [Member] | Capitalized Data [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Losses, non-financial instruments		882
Fair Value, Measurements, Nonrecurring [Member] | Goodwill [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Losses, non-financial instruments				3,900
Fair Value, Measurements, Nonrecurring [Member] | Equity Method Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total Losses, non-financial instruments		23,431		360
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property and equipment, net		0	0	0
Capitalized data and database developement costs net		0
Goodwill				0
Investment in affiliates, net		0		0
Non-financial instruments		0		0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property and equipment, net		0	0	0
Capitalized data and database developement costs net		0
Goodwill				0
Investment in affiliates, net		0		0
Non-financial instruments		0		0
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property and equipment, net		0	$ 0	0
Capitalized data and database developement costs net		0
Goodwill				0
Investment in affiliates, net		5,662		0
Non-financial instruments		$ 5,662		$ 0
FNC, Inc. [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Amount paid to acquire business	$ 400,000
Business Combination, Contingent Consideration, Liability	8,000
Maximum [Member] | FNC, Inc. [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Payments to Acquire Businesses	$ 75,000