GUARANTOR - Condensed Shareholder's Equity (Details) - USD ($)	3 Months Ended													9 Months Ended	12 Months Ended
	Dec. 31, 2016	Oct. 16, 2016	Sep. 30, 2016	Jul. 16, 2016	Jun. 30, 2016	Apr. 16, 2016	Mar. 31, 2016	Jan. 16, 2016	Dec. 31, 2015	Oct. 16, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Oct. 01, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Financial Statements, Captions [Line Items]
Opening Balance VALUE							$ 361,450,000						$ 329,021,000	$ 393,374,000	$ 361,450,000	$ 329,021,000	$ 298,393,000
Net income (loss)	$ 11,399,000		$ 11,420,000		$ 10,834,000		4,412,000		$ 14,088,000		$ 8,442,000	$ 6,747,000	(93,000)		38,065,000	29,184,000	26,823,000	$ 26,823,000
Conversion of Class B common stock to Class A common stock (Share)														3,152,333
Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures															6,539,000	5,524,000	5,232,000
Issuance of common stock related to an incentive plan VALUE															379,000	0	0
Common stock repurchase VALUE															0	0	0
Purchase of vested employee restricted stock units															$ (2,268,000)	$ (1,562,000)	$ (1,514,000)
Purchase of vested employee restricted stock units SHARES															(232,000)	(132,000)	(142,000)
Forfeitures of dividend equivalents VALUE															$ 0	$ 0	$ 5,000
Realization of tax benefit for dividend equivalent payments VALUE																0	0
Net unrealized gain (loss) on derivatives VALUE															$ 0		0
Exercise of stock options SHARES															134,238
Exercise of stock options VALUE															$ 265,000	35,000	82,000
Ending Balance VALUE	393,374,000								361,450,000						393,374,000	361,450,000	329,021,000	$ 298,393,000
PreferredStockDividendsIncomeStatementImpact	550,000		413,000		413,000		412,000		413,000		0	0	0		1,901,000	752,000	0
DividendsPreferredStockCash		$ 550,000		$ 412,500		$ 412,500		$ 412,500		$ 412,500					1,788,000	752,000	0
Payments Of Dividends	$ 2,893,000		$ 2,887,000		$ 2,886,000		0		$ 0		$ 0	$ 0	0		(8,666,000)
Common Class A [Member]
Condensed Financial Statements, Captions [Line Items]
Opening Balance VALUE							$ 325,000						$ 319,000	$ 335,000	$ 325,000	$ 319,000	$ 313,000
Opening Balance SHARES							32,480,551						31,862,294	33,510,184	32,480,551	31,862,294	31,308,194
Stock Issued During Period Shares Restricted Stock Award Net Of Forfeitures															1,095,759	738,195	638,102
Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures															$ 11,000	$ 7,000	$ 7,000
Stock Issued During Period Shares Employee Stock Purchase Plans															31,933	0	0
Issuance of common stock related to an incentive plan VALUE															$ 0	$ 0	$ 0
Common stock repurchase SHARES																0	0
Common stock repurchase VALUE															0	$ 0	$ 0
Purchase of vested employee restricted stock units															$ (2,000)	$ (1,000)	$ (1,000)
Purchase of vested employee restricted stock units SHARES															(232,297)	(131,688)	(141,502)
Forfeitures of dividend equivalents VALUE															$ 0	$ 0	$ 0
Realization of tax benefit for dividend equivalent payments VALUE																0	$ 0
Net unrealized gain (loss) on derivatives VALUE															$ 0	$ 0
Exercise of stock options SHARES															134,238	11,750	57,500
Exercise of stock options VALUE															$ 1,000	$ 0	$ 0
Ending Balance SHARES	33,510,184								32,480,551						33,510,184	32,480,551	31,862,294	31,308,194
Ending Balance VALUE	$ 335,000								$ 325,000						$ 335,000	$ 325,000	$ 319,000	$ 313,000
DividendsPreferredStockCash															0
Payments Of Dividends															0
Common Class B [Member]
Condensed Financial Statements, Captions [Line Items]
Opening Balance VALUE							$ 72,000						$ 72,000	$ 72,000	$ 72,000	$ 72,000	$ 72,000
Opening Balance SHARES							7,197,532						7,197,532	7,197,532	7,197,532	7,197,532	7,197,532
Stock Issued During Period Shares Restricted Stock Award Net Of Forfeitures															0	0	0
Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures															$ 0	$ 0	$ 0
Stock Issued During Period Shares Employee Stock Purchase Plans															0	0	0
Issuance of common stock related to an incentive plan VALUE															$ 0	$ 0	$ 0
Common stock repurchase SHARES																0	0
Common stock repurchase VALUE															0	$ 0	$ 0
Purchase of vested employee restricted stock units															$ 0	$ 0	$ 0
Purchase of vested employee restricted stock units SHARES															0	0	0
Forfeitures of dividend equivalents VALUE															$ 0	$ 0	$ 0
Realization of tax benefit for dividend equivalent payments VALUE																0	0
Net unrealized gain (loss) on derivatives VALUE															$ 0	$ 0	$ 0
Exercise of stock options SHARES															0	0	0
Exercise of stock options VALUE															$ 0	$ 0	$ 0
Ending Balance SHARES	7,197,532								7,197,532						7,197,532	7,197,532	7,197,532	7,197,532
Ending Balance VALUE	$ 72,000								$ 72,000						$ 72,000	$ 72,000	$ 72,000	$ 72,000
DividendsPreferredStockCash															0
Payments Of Dividends															0
Additional Paid In Capital [Member]
Condensed Financial Statements, Captions [Line Items]
Opening Balance VALUE							$ 611,754,000						$ 608,515,000	$ 605,603,000	611,754,000	608,515,000	604,721,000
Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures															6,528,000	5,517,000	5,225,000
Issuance of common stock related to an incentive plan VALUE															379,000	0	0
Common stock repurchase VALUE															0	0	0
Purchase of vested employee restricted stock units															(2,266,000)	(1,561,000)	(1,513,000)
Forfeitures of dividend equivalents VALUE															0	0	0
Realization of tax benefit for dividend equivalent payments VALUE																0	0
Net unrealized gain (loss) on derivatives VALUE															0		0
Exercise of stock options VALUE															264,000	35,000	82,000
Ending Balance VALUE	605,603,000								611,754,000						605,603,000	611,754,000	608,515,000	604,721,000
DividendsPreferredStockCash															1,788,000	752,000
Payments Of Dividends															(8,666,000)
Retained Earnings [Member]
Condensed Financial Statements, Captions [Line Items]
Opening Balance VALUE							(250,701,000)						(279,885,000)	(212,636,000)	(250,701,000)	(279,885,000)	(306,713,000)
Net income (loss)															38,065,000	29,184,000	26,823,000
Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures															0	0	0
Issuance of common stock related to an incentive plan VALUE															0	0	0
Common stock repurchase VALUE															0	0	0
Purchase of vested employee restricted stock units															0	0	0
Forfeitures of dividend equivalents VALUE															0	0	5,000
Realization of tax benefit for dividend equivalent payments VALUE																0	0
Net unrealized gain (loss) on derivatives VALUE															0	0	0
Exercise of stock options VALUE															0	0	0
Ending Balance VALUE	(212,636,000)								(250,701,000)						(212,636,000)	(250,701,000)	(279,885,000)	(306,713,000)
DividendsPreferredStockCash															0
Payments Of Dividends															0
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Opening Balance VALUE							361,450,000						329,021,000	393,374,000	361,450,000	329,021,000	298,393,000
Net income (loss)															38,065,000	29,184,000	26,823,000
Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures															6,539,000	5,524,000	5,232,000
Issuance of common stock related to an incentive plan VALUE															379,000
Purchase of vested employee restricted stock units															(2,268,000)	(1,562,000)	(1,514,000)
Forfeitures of dividend equivalents VALUE															(602,000)	0	5,000
Realization of tax benefit for dividend equivalent payments VALUE																0	0
Net unrealized gain (loss) on derivatives VALUE															0		0
Exercise of stock options VALUE															265,000	35,000	82,000
Ending Balance VALUE	$ 393,374,000								$ 361,450,000						393,374,000	361,450,000	329,021,000	$ 298,393,000
PreferredStockDividendsIncomeStatementImpact															(1,901,000)	(752,000)	0
DividendsPreferredStockCash															(1,788,000)	(752,000)
Payments Of Dividends															(8,666,000)
Parent Company [Member] | Common Class A [Member]
Condensed Financial Statements, Captions [Line Items]
Opening Balance VALUE							$ 325,000						$ 319,000	$ 335,000	$ 325,000	$ 319,000	$ 313,000
Opening Balance SHARES							32,480,551						31,862,294	33,510,184	32,480,551	31,862,294	31,308,194
Stock Issued During Period Shares Restricted Stock Award Net Of Forfeitures															1,095,759	738,195	638,102
Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures															$ 11,000	$ 7,000	$ 7,000
Stock Issued During Period Shares Employee Stock Purchase Plans															31,933
Issuance of common stock related to an incentive plan VALUE															$ 0
Purchase of vested employee restricted stock units															$ (2,000)	$ (1,000)	$ (1,000)
Purchase of vested employee restricted stock units SHARES															(232,297)	(131,688)	(141,502)
Forfeitures of dividend equivalents VALUE															$ 0	$ 0	$ 0
Realization of tax benefit for dividend equivalent payments VALUE																0	0
Net unrealized gain (loss) on derivatives VALUE															$ 0	$ 0	$ 0
Exercise of stock options SHARES															134,238,000	11,750	57,500
Exercise of stock options VALUE															$ 1,000	$ 0	$ 0
Ending Balance SHARES	33,510,184								32,480,551						33,510,184	32,480,551	31,862,294	31,308,194
Ending Balance VALUE	$ 335,000								$ 325,000						$ 335,000	$ 325,000	$ 319,000	$ 313,000
Parent Company [Member] | Common Class B [Member]
Condensed Financial Statements, Captions [Line Items]
Opening Balance VALUE							$ 72,000						$ 72,000	$ 72,000	$ 72,000	$ 72,000	$ 72,000
Opening Balance SHARES							7,197,532						7,197,532	7,197,532	7,197,532	7,197,532	7,197,532
Stock Issued During Period Shares Restricted Stock Award Net Of Forfeitures															0	0	0
Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures															$ 0	$ 0	$ 0
Stock Issued During Period Shares Employee Stock Purchase Plans															0
Issuance of common stock related to an incentive plan VALUE															$ 0
Purchase of vested employee restricted stock units															$ 0	$ 0	$ 0
Purchase of vested employee restricted stock units SHARES															0	0	0
Forfeitures of dividend equivalents VALUE															$ 0	$ 0	$ 0
Realization of tax benefit for dividend equivalent payments VALUE																0	0
Net unrealized gain (loss) on derivatives VALUE															0	$ 0	$ 0
Exercise of stock options SHARES																0	0
Exercise of stock options VALUE															$ 0	$ 0	$ 0
Ending Balance SHARES	7,197,532								7,197,532						7,197,532	7,197,532	7,197,532	7,197,532
Ending Balance VALUE	$ 72,000								$ 72,000						$ 72,000	$ 72,000	$ 72,000	$ 72,000
Parent Company [Member] | Additional Paid In Capital [Member]
Condensed Financial Statements, Captions [Line Items]
Opening Balance VALUE							$ 611,754,000						$ 608,515,000	$ 605,603,000	611,754,000	608,515,000	604,721,000
Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures															6,528,000	5,517,000	5,225,000
Issuance of common stock related to an incentive plan VALUE															379,000
Purchase of vested employee restricted stock units															(2,266,000)	(1,561,000)	(1,513,000)
Forfeitures of dividend equivalents VALUE															(602,000)	0	0
Realization of tax benefit for dividend equivalent payments VALUE																0	0
Net unrealized gain (loss) on derivatives VALUE															0		0
Exercise of stock options VALUE															264,000	35,000	82,000
Ending Balance VALUE	605,603,000								611,754,000						605,603,000	611,754,000	608,515,000	604,721,000
DividendsPreferredStockCash															(1,788,000)	(752,000)
Payments Of Dividends															(8,666,000)
Parent Company [Member] | Retained Earnings [Member]
Condensed Financial Statements, Captions [Line Items]
Opening Balance VALUE							$ (250,701,000)						$ (279,885,000)	$ (212,636,000)	(250,701,000)	(279,885,000)	(306,713,000)
Net income (loss)															38,065,000	29,184,000	26,823,000
Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures															0	0	0
Issuance of common stock related to an incentive plan VALUE															0
Purchase of vested employee restricted stock units															0	0	0
Forfeitures of dividend equivalents VALUE															0	0	5,000
Realization of tax benefit for dividend equivalent payments VALUE																0	0
Net unrealized gain (loss) on derivatives VALUE															0	0	0
Exercise of stock options VALUE															0	0	0
Ending Balance VALUE	$ (212,636,000)								$ (250,701,000)						$ (212,636,000)	$ (250,701,000)	$ (279,885,000)	$ (306,713,000)