CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
ASSETS
Accounts receivable, trade allowance for doubtful accounts	$ 15,881	$ 13,520
Property, plant and equipment, accumulated depreciation	4,704,512	4,044,671
Amortizable intangible assets, accumulated amortization	$ 3,284,685	$ 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)	655,226,030
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)	468,084,705	496,064,027
Common stock, shares outstanding (in shares)	468,068,226	496,064,027
Treasury stock (in shares)	16,479
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)	187,157,804	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