CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Accounts receivable, allowance for doubtful accounts	$ 74	$ 71
Property and equipment, accumulated depreciation	1,363	1,367
Customer relationships, accumulated amortization	5,399	5,299
Other intangibles, accumulated amortization	$ 2,215	$ 2,134
Class A common stock
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, authorized shares (in shares)	1,600,000,000	1,600,000,000
Common stock, issued shares (in shares)	182,811,430	179,873,244
Common stock, outstanding shares (in shares)	182,811,430	179,873,244
Class B common stock
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, authorized shares (in shares)	800,000,000	800,000,000
Common stock, issued shares (in shares)	723,570,588	719,330,114
Common stock, outstanding shares (in shares)	723,570,588	719,330,114