Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Thousands, $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Accounts receivable, allowances	$ 20,650	$ 19,087
Property and equipment, accumulated depreciation	$ 311,897	$ 284,126
Common stock, par value (in usd per share)	$ 2	$ 2
Common stock, authorized (shares)	200,000	200,000
Common stock, issued (shares)	75,395	73,472
Common stock, outstanding (shares)	75,395	73,472