CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common stock	Additional paid-in capital	Retained earnings	Accumulated other comprehensive income (loss)	Treasury stock	Noncontrolling interest in consolidated subsidiaries
Beginning balance at Dec. 31, 2016	$ 982,586	$ 27,900	$ 0	$ 1,874,722	$ (346,359)	$ (612,781)	$ 39,104
Increase (Decrease) in Shareholders' Equity
Net earnings	39,961			38,979			982
Other comprehensive income (loss)	18,883				20,106		(1,223)
Cash dividends declared	(8,468)			(8,468)			0
Dividends to noncontrolling interests	(422)						(422)
Stock plan exercises	(2,870)					(2,870)
Stock options exercised	8,894		(2,494)	928		10,460
Stock option expense	1,289		1,289
Stock awards	1,427		1,205			222
Ending balance at Apr. 01, 2017	1,041,280	27,900	0	1,906,161	(326,253)	(604,969)	38,441
Increase (Decrease) in Shareholders' Equity
Cumulative impact of ASC 606 adoption	9,771			9,771
Beginning balance at Dec. 30, 2017	1,151,795	27,900	0	1,954,344	(279,022)	(590,386)	38,959
Increase (Decrease) in Shareholders' Equity
Net earnings	40,480			39,281			1,199
Other comprehensive income (loss)	5,941				2,393		3,548
Cash dividends declared	(8,493)			(8,493)			0
Dividends to noncontrolling interests	(1,281)						(1,281)
Purchase of noncontrolling interests	5,510		0				5,510
Addition of noncontrolling interest	3,200						3,200
Purchase of treasury shares	(14,790)					(14,790)
Stock plan exercises	(1,504)					(1,504)
Stock options exercised	2,972		(2,545)	1,571		3,946
Stock option expense	1,090		1,090
Stock awards	1,685		1,455			230
Ending balance at Mar. 31, 2018	$ 1,185,356	$ 27,900	$ 0	$ 1,996,474	$ (276,629)	$ (602,504)	$ 40,115