STATEMENTS OF SHAREHOLDERS' EQUITY (UNAUDITED) - USD ($) $ in Thousands		Total	Class A common stock	Class B common stock	Common stock Class A common stock	Common stock Class B common stock	Additional paid-in-capital	Accumulated other comprehensive income (loss)	Retained earnings	Retained earnings Class A common stock	Retained earnings Class B common stock	Treasury stock	Deferred compensation
Beginning balance at Dec. 31, 2017		$ 857,344			$ 1,992	$ 178	$ 16,470	$ (156,059)	$ 2,140,853			$ (1,155,668)	$ 9,578
Increase (decrease) in shareholders' equity
Net income		65,758							65,758
Other comprehensive income (loss)		(5,427)						(5,427)
Dividends declared:			$ (38,799)	$ (320)						$ (38,799)	$ (320)
Net purchase of treasury stock	[1]	(9)					(9)					0
Deferred compensation		0										(1,663)	1,663
Ending balance at Mar. 31, 2018		840,155			1,992	178	16,461	(161,486)	2,129,100			(1,157,331)	11,241
Beginning balance at Dec. 31, 2017		857,344			1,992	178	16,470	(156,059)	2,140,853			(1,155,668)	9,578
Increase (decrease) in shareholders' equity
Net income		225,910
Other comprehensive income (loss)		(6,470)						(6,470)
Ending balance at Sep. 30, 2018		921,023			1,992	178	16,459	(162,529)	2,211,013			(1,157,310)	11,220
Beginning balance at Mar. 31, 2018		840,155			1,992	178	16,461	(161,486)	2,129,100			(1,157,331)	11,241
Increase (decrease) in shareholders' equity
Net income		79,706							79,706
Other comprehensive income (loss)		(551)						(551)
Dividends declared:			(38,799)	(321)						(38,799)	(321)
Net purchase of treasury stock	[1]	(2)					(2)					0
Deferred compensation		0										(276)	276
Rabbi trust distribution	[2]	0										608	(608)
Ending balance at Jun. 30, 2018		880,188			1,992	178	16,459	(162,037)	2,169,686			(1,156,999)	10,909
Increase (decrease) in shareholders' equity
Net income		80,446							80,446
Other comprehensive income (loss)		(492)						(492)
Dividends declared:			(38,799)	(320)						(38,799)	(320)
Net purchase of treasury stock	[1]	0					0					0
Deferred compensation		0										(311)	311
Ending balance at Sep. 30, 2018		921,023			1,992	178	16,459	(162,529)	2,211,013			(1,157,310)	11,220
Beginning balance at Dec. 31, 2018		973,672			1,992	178	16,459	(130,284)	2,231,417			(1,157,625)	11,535
Increase (decrease) in shareholders' equity
Net income		75,311							75,311
Other comprehensive income (loss)		6,710						6,710
Dividends declared:			(41,570)	(343)						(41,570)	(343)
Net purchase of treasury stock	[3]	24					24					0
Deferred compensation		0										(1,154)	1,154
Ending balance at Mar. 31, 2019		1,013,804			1,992	178	16,483	(123,574)	2,264,815			(1,158,779)	12,689
Beginning balance at Dec. 31, 2018		973,672			1,992	178	16,459	(130,284)	2,231,417			(1,157,625)	11,535
Increase (decrease) in shareholders' equity
Net income		257,234
Other comprehensive income (loss)		14,081						14,081
Ending balance at Sep. 30, 2019		1,119,271			1,992	178	16,483	(116,203)	2,362,911			(1,158,620)	12,530
Beginning balance at Mar. 31, 2019		1,013,804			1,992	178	16,483	(123,574)	2,264,815			(1,158,779)	12,689
Increase (decrease) in shareholders' equity
Net income		87,754							87,754
Other comprehensive income (loss)		3,810						3,810
Dividends declared:			(41,570)	(344)						(41,570)	(344)
Net purchase of treasury stock	[3]	0					0					0
Deferred compensation		0										(443)	443
Rabbi trust distribution	[4]	0										922	(922)
Ending balance at Jun. 30, 2019		1,063,454			1,992	178	16,483	(119,764)	2,310,655			(1,158,300)	12,210
Increase (decrease) in shareholders' equity
Net income		94,169							94,169
Other comprehensive income (loss)		3,561						3,561
Dividends declared:			$ (41,570)	$ (343)						$ (41,570)	$ (343)
Net purchase of treasury stock	[3]	0					0					0
Deferred compensation		0										(320)	320
Ending balance at Sep. 30, 2019		$ 1,119,271			$ 1,992	$ 178	$ 16,483	$ (116,203)	$ 2,362,911			$ (1,158,620)	$ 12,530

[1] Net purchases of treasury stock in 2018 include the repurchase of our Class A common stock in the open market that were subsequently distributed to satisfy stock based compensation awards. See Note 11, "Capital Stock", for additional information on treasury stock transactions.

[2] Distributions of our Class A shares were made from the rabbi trust to a retired director in 2018.

[3] Net purchases of treasury stock in 2019 include the repurchase of our Class A common stock in the open market that were subsequently distributed to satisfy stock based compensation awards. See Note 11, "Capital Stock", for additional information on treasury stock transactions.

[4] Distributions of our Class A shares were made from the rabbi trust to a retired director in 2019.