CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
ASSETS
Accounts receivable, trade allowance for doubtful accounts	$ 13,694	$ 13,520
Property, plant and equipment, accumulated depreciation	5,058,198	4,044,671
Amortizable intangible assets, accumulated amortization	$ 3,476,043	$ 2,882,787
Stockholders' Equity:
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	100,000,000	100,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, shares outstanding (in shares)	636,827,486
Common Class A
Stockholders' Equity:
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	4,000,000,000	4,000,000,000
Common stock, shares issued (in shares)	450,565,544	496,064,027
Common stock, shares outstanding (in shares)	450,564,558	496,064,027
Treasury stock (in shares)	986
Common Class B
Stockholders' Equity:
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	1,000,000,000	1,000,000,000
Common stock, shares issued (in shares)	490,086,674	490,086,674
Common stock, shares outstanding (in shares)	186,262,928	212,976,259
Common Class C
Stockholders' Equity:
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	4,000,000,000	4,000,000,000
Common stock, shares issued (in shares)	0	0
Common stock, shares outstanding (in shares)	0	0