CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current Assets:
Allowance for doubtful accounts on trade accounts receivable - other	$ 22,167	$ 23,603
Class A common stock
Current Assets:
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	1,600,000,000	1,600,000,000
Common stock, shares issued	281,866,884	279,406,646
Common stock, shares outstanding	225,748,624	223,288,386
Class B common stock
Current Assets:
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	800,000,000	800,000,000
Common stock, shares issued	238,435,208	238,435,208
Common stock, shares outstanding	238,435,208	238,435,208