Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Allowance for doubtful accounts	$ 2,803	$ 2,642
Treasury stock, shares	376,022,975	374,578,057
Common Stock Issued
Class A common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Class A common stock, shares authorized	2,000,000,000	2,000,000,000
Class A common stock, shares issued	544,003,038	544,003,038
Class A common stock, shares outstanding	167,980,063	169,424,981