Condensed Consolidated Statement of Stockholders' Equity (Unaudited) - 9 months ended Sep. 30, 2015 - 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]	2007 Incentive Plan [Member] Common Stock [Member] Common Class A [Member]	2007 Incentive Plan [Member] Common Stock [Member]	2007 Incentive Plan [Member] Retained Earnings [Member]	2007 Incentive Plan [Member] Treasury Stock [Member] Common Class A [Member]	2007 Incentive Plan [Member] Treasury Stock [Member]	2007 Incentive Plan [Member] AOCI Attributable to Parent [Member]	2007 Incentive Plan [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, 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
Net income																	$ 24,314,000				24,314,000
Adjustment to pension liability, net of income tax																				$ 7,494,000	7,494,000
Underwritten public offering (in shares)																13,511,040
Underwritten public offering																$ 167,313,000					167,313,000
Issuance of common stock, Employee Benefit Plan (in shares)		1,459						287,513	150,308		(32,817)	(67,989)
Issuance of common stock, Employee Benefit Plan		$ 19,000					$ 19,000				$ (287,000)	$ (818,000)		$ (1,105,000)
Share-based compensation															$ 1,648,000	$ 1,363,000					3,011,000
Balance (in shares) at Sep. 30, 2015															7,855,381	70,988,987		(1,611,371)	(4,882,705)
Balance at Sep. 30, 2015															$ 18,744,000	$ 655,012,000	$ (178,625,000)	$ (22,685,000)	$ (41,890,000)	$ (13,318,000)	$ 417,238,000