CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 30, 2018
Accounts receivable, allowances	$ 13,334	$ 13,249
Accumulated depreciation and amortization	$ 926,280	$ 911,845
Common stock, par value (in usd per share)	$ 0.1	$ 0.1
Class A Common Stock
Authorized shares (in shares)	300,000,000	300,000,000
Issued shares (in shares)	174,017,535	173,158,414
Treasury shares (in shares)	8,870,801	8,870,801
Class B Common Stock
Authorized shares (in shares)	803,408	803,408
Issued shares (in shares)	803,408	803,408