Consolidated Statement of Stockholders' Equity - USD ($)	401(k) Plan [Member] Common Stock [Member] Common Class A [Member]	401(k) Plan [Member] Common Stock [Member]	401(k) Plan [Member] Retained Earnings [Member]	401(k) Plan [Member] Treasury Stock [Member] Common Class A [Member]	401(k) Plan [Member] Treasury Stock [Member]	401(k) Plan [Member] AOCI Attributable to Parent [Member]	401(k) Plan [Member]	Restricted Stock [Member] Common Stock [Member] Common Class A [Member]	Restricted Stock [Member] Common Stock [Member]	Restricted Stock [Member] Retained Earnings [Member]	Restricted Stock [Member] Treasury Stock [Member] Common Class A [Member]	Restricted Stock [Member] Treasury Stock [Member]	Restricted Stock [Member] AOCI Attributable to Parent [Member]	Restricted Stock [Member]	Common Stock [Member] Common Class A [Member]	Common Stock [Member]	Retained Earnings [Member]	Treasury Stock [Member] Common Class A [Member]	Treasury Stock [Member]	AOCI Attributable to Parent [Member]	Total
Balance (in shares) at Dec. 31, 2012															7,331,574	56,503,759		(1,578,554)	(4,739,462)
Balance at Dec. 31, 2012															$ 15,321,000	$ 480,773,000	$ (269,288,000)	$ (22,398,000)	$ (40,303,000)	$ (20,170,000)	$ 143,935,000
Net income															0	0	18,288,000	0	0	0	18,288,000
Adjustment to pension liability, net of income tax															$ 0	$ 0	0	$ 0	$ 0	9,761,000	$ 9,761,000
401(k) plan (in shares)	0	5,235		0	0																5,235
401(k) plan	$ 0	$ 28,000	$ 0	$ 0	$ 0	$ 0	$ 28,000														$ 28,000
Restricted stock awards (in shares)								0	382,062		0	(29,463)
Restricted stock awards								$ 0	$ 0	$ 0	$ 0	$ (256,000)	$ 0	$ (256,000)
Option exercises (in shares)															0	119,822		0	0		119,822
Option exercises															$ 0	$ 280,000	0	$ 0	$ 0	0	$ 280,000
Amortization of restricted stock and stock option awards															$ 0	$ 1,974,000	0	$ 0	$ 0	0	1,974,000
Balance (in shares) at Dec. 31, 2013															7,331,574	57,010,878		(1,578,554)	(4,768,925)
Balance at Dec. 31, 2013															$ 15,321,000	$ 483,055,000	(251,000,000)	$ (22,398,000)	$ (40,559,000)	(10,409,000)	174,010,000
Adjustment to pension liability, net of income tax															0	0	0	0	0	9,761,000	9,761,000
Net income															0	0	18,288,000	0	0	0	18,288,000
Restricted stock awards								$ 0	$ 0	0	$ 0	$ (256,000)	0	(256,000)
Net income															0	0	48,061,000	0	0	0	48,061,000
Adjustment to pension liability, net of income tax															0	0	0	0	0	(10,403,000)	$ (10,403,000)
401(k) plan (in shares)	0	2,341		0	0																2,341
401(k) plan	$ 0	$ 25,000	0	$ 0	$ 0	0	25,000														$ 25,000
Restricted stock awards (in shares)								236,294	312,961		0	(45,791)
Restricted stock awards								$ 0	$ 0	0	$ 0	$ (513,000)	0	(513,000)
Amortization of restricted stock and stock option awards															$ 1,775,000	$ 3,237,000	0	$ 0	$ 0	0	5,012,000
Balance (in shares) at Dec. 31, 2014															7,567,868	57,326,180		(1,578,554)	(4,814,716)
Balance at Dec. 31, 2014															$ 17,096,000	$ 486,317,000	(202,939,000)	$ (22,398,000)	$ (41,072,000)	(20,812,000)	216,192,000
Adjustment to pension liability, net of income tax															0	0	0	0	0	(10,403,000)	(10,403,000)
Net income															0	0	48,061,000	0	0	0	48,061,000
Restricted stock awards								$ 0	$ 0	$ 0	$ 0	$ (513,000)	$ 0	$ (513,000)
Net income															0	0	39,301,000	0	0	0	39,301,000
Adjustment to pension liability, net of income tax															$ 0	$ 0	0	$ 0	$ 0	3,528,000	$ 3,528,000
401(k) plan (in shares)	0	1,898		0	0																1,898
401(k) plan	$ 0	$ 26,000	$ 0	$ 0	$ 0	$ 0	$ 26,000														$ 26,000
Restricted stock awards (in shares)															287,513	150,308		(32,817)	(67,989)
Restricted stock awards															$ 0	$ 0	0	$ (287,000)	$ (818,000)	0	(1,105,000)
Amortization of restricted stock and stock option awards															$ 2,229,000	$ 1,790,000	0	$ 0	$ 0	0	4,019,000
Balance (in shares) at Dec. 31, 2015															7,855,381	70,989,426		(1,611,371)	(4,882,705)
Balance at Dec. 31, 2015															$ 19,325,000	$ 655,446,000	(163,638,000)	$ (22,685,000)	$ (41,890,000)	(17,284,000)	429,274,000
Adjustment to pension liability, net of income tax															0	0	0	0	0	3,528,000	3,528,000
Net income															$ 0	$ 0	39,301,000	$ 0	$ 0	0	39,301,000
Stock Issued During Period, Shares, New Issues															0	13,511,040		0	0
Underwritten public offering															$ 0	$ 167,313,000	0	$ 0	$ 0	0	167,313,000
Restricted stock awards															$ 0	$ 0	$ 0	$ (287,000)	$ (818,000)	$ 0	$ (1,105,000)