Consolidated Statements of Changes in Shareholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Additional Paid in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Common Class A	Common Class B
Beginning balance (in shares) at Dec. 31, 2014						30,150	17,443
Beginning balance at Dec. 31, 2014	$ 1,063,574	$ 1,081,628	$ 158,403	$ (3,824)	$ (173,190)	$ 370	$ 187
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	11,389		11,389
Other comprehensive income, net of tax expense	4,098			4,098
Stock-based compensation	284	284
Purchase of treasury stock (in shares)						(487)	(474)
Purchase of treasury stock	(24,996)				(24,996)
Conversion of shares (in shares)						374	(374)
Conversion of shares						$ 3	$ (3)
Ending balance (in shares) at Mar. 31, 2015						30,037	16,595
Ending balance at Mar. 31, 2015	1,054,349	1,081,912	169,792	274	(198,186)	$ 373	$ 184
Beginning balance (in shares) at Dec. 31, 2015						26,589	16,554
Beginning balance at Dec. 31, 2015	986,265	1,076,415	208,742	(5,196)	(294,249)	$ 370	$ 183
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	9,840		9,840
Dividends paid	(4,314)		(4,314)
Other comprehensive income, net of tax expense	9,074			9,074
Stock-based compensation	317	317
Restricted stock grants (in shares)						184
Restricted stock grants	$ 2					$ 2
Nonqualified stock option exercise (in shares)	10
Nonqualified stock option exercise	$ 199	199
Purchase of treasury stock (in shares)						(148)
Purchase of treasury stock	(4,390)				(4,390)
Ending balance (in shares) at Mar. 31, 2016						26,635	16,554
Ending balance at Mar. 31, 2016	$ 996,993	$ 1,076,931	$ 214,268	$ 3,878	$ (298,639)	$ 372	$ 183