CONSOLIDATED BALANCE SHEETS (unaudited) (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Accounts receivable, allowance	$ 242,462	$ 252,056
Property and equipment, accumulated depreciation	2,954,237	2,832,160
Intangible assets, accumulated amortization	$ 987,468	$ 940,731
Preferred stock, par value (usd per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, issued (in shares)	0	0
Common stock, par value (usd per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	450,000,000	450,000,000
Common stock, shares issued (in shares)	194,596,120	194,554,491
Common stock, shares outstanding (in shares)	194,596,120	194,554,491