Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Statement of Financial Position [Abstract]
Allowance for doubtful accounts receivable	$ 4,810	$ 4,371
Accumulated amortization	$ 313,593	$ 298,593
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock, authorized shares (in shares)	800,000,000	800,000,000
Common stock, issued shares (in shares)	324,418,632	324,418,632
Treasury stock, shares (in shares)	101,681,915	103,012,455