CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
CONSOLIDATED BALANCE SHEETS
Accounts receivable, allowance for doubtful accounts (in dollars)	$ 11,105	$ 14,779
Accumulated depreciation	$ 868,036	$ 884,647
Preferred shares, authorized	5,000,000	5,000,000
Preferred shares, issued	0	0
Preferred shares, outstanding	0	0
Common shares, authorized	240,000,000	240,000,000
Common shares, issued	98,581,434	98,581,434
Common shares, outstanding	58,786,776	59,640,895
Treasury shares	39,794,658	38,940,539