GUARANTOR - Condensed Shareholder's Equity (Details) - USD ($)	1 Months Ended	3 Months Ended																12 Months Ended
	Nov. 17, 2017	Dec. 31, 2017	Oct. 16, 2017	Sep. 30, 2017	Jul. 16, 2017	Jun. 30, 2017	Apr. 16, 2017	Mar. 31, 2017	Jan. 16, 2017	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, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2013	Jan. 01, 2017
Condensed Financial Statements, Captions [Line Items]
Opening Balance VALUE								$ 393,374,000								$ 361,450,000		$ 393,374,000	$ 361,450,000	$ 329,021,000
Net income (loss)		$ 232,413,000		$ 3,437,000		$ 5,864,000		(9,881,000)		$ 10,849,000		$ 10,894,000		$ 10,422,000		3,999,000		$ 233,849,000	38,065,000	29,184,000	$ 29,184,000
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																		$ 9,567,000	6,539,000	5,524,000
Issuance of common stock related to an incentive plan VALUE																		182,000	379,000	0
Common stock repurchase VALUE																		10,675,000	0	0
Purchase of vested employee restricted stock units																		$ (2,565,000)	$ (2,268,000)	$ (1,562,000)
Purchase of vested employee restricted stock units SHARES																		(169,000)	(232,000)	(132,000)
Forfeitures of dividend equivalents VALUE																				$ 0
Realization of tax benefit for dividend equivalent payments VALUE																				0
Net unrealized gain (loss) on derivatives VALUE																		$ 5,112,000
Exercise of stock options SHARES																		8,250
Exercise of stock options VALUE																		$ 42,000	$ 265,000	35,000
Ending Balance VALUE		1,764,360,000								393,374,000								1,764,360,000	393,374,000	361,450,000
PreferredStockDividendsIncomeStatementImpact		252,000		663,000		550,000		550,000		550,000		526,000		412,000		413,000		2,015,000	1,901,000	752,000
DividendsPreferredStockCash	$ 236,806		$ 687,500		$ 550,000		$ 550,000		$ 550,000		$ 550,000		$ 412,500		$ 412,500		$ 412,500	2,574,000	1,788,000	752,000
Payments Of Dividends		$ 12,746,000		$ 10,713,000		$ 2,921,000		2,916,000		$ 2,893,000		$ 2,887,000		$ 2,886,000		0		(29,296,000)	(8,666,000)
Equity awards assumed in Merger VALUE																		6,777,000
StockIssuedDuringPeriodValueAcquisitions																		1,161,116,000
Stock options assumed in Merger VALUE																		1,007,000
Dividend equivalents, net of forfeitures																		(1,556,000)	(602,000)
Common Class A [Member]
Condensed Financial Statements, Captions [Line Items]
Opening Balance VALUE								$ 335,000								$ 325,000		$ 335,000	$ 325,000	$ 319,000
Opening Balance SHARES								33,510,184								32,480,551		33,510,184	32,480,551	31,862,294
Net income (loss)																		$ 0	$ 0	$ 0
Stock Granted During Period, Value, Share-based Compensation, Net of Forfeitures																		$ 0
Stock Issued During Period Shares Restricted Stock Award Net Of Forfeitures																		2,066,241	1,095,759	738,195
Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures																		$ 21,000	$ 11,000	$ 7,000
Stock Issued During Period Shares Employee Stock Purchase Plans																		14,833	31,933	0
Issuance of common stock related to an incentive plan VALUE																		$ 0	$ 0	$ 0
Common stock repurchase SHARES																		932,600	0	0
Common stock repurchase VALUE																		$ 9,000	$ 0	$ 0
Purchase of vested employee restricted stock units																		$ (2,000)	$ (2,000)	$ (1,000)
Purchase of vested employee restricted stock units SHARES																		(169,279)	(232,297)	(131,688)
Forfeitures of dividend equivalents VALUE																				$ 0
Realization of tax benefit for dividend equivalent payments VALUE																				$ 0
Net unrealized gain (loss) on derivatives VALUE																		$ 0
Exercise of stock options SHARES																		8,250	134,238	11,750
Exercise of stock options VALUE																		$ 0	$ 1,000	$ 0
Ending Balance SHARES		139,675,781								33,510,184								139,675,781	33,510,184	32,480,551
Ending Balance VALUE		$ 1,397,000								$ 335,000								$ 1,397,000	$ 335,000	$ 325,000
DividendsPreferredStockCash																		0	0	$ 0
Payments Of Dividends																		0	$ 0
Conversion Of Common Class B To Common Classa Value																		$ 32,000
Conversion Of Stock Shares Converted 2010																		3,152,333	0	0
Equity awards assumed in Merger VALUE																		$ 6,000
StockIssuedDuringPeriodSharesAcquisitions																		101,407,494
StockIssuedDuringPeriodValueAcquisitions																		$ 1,014,000
Stock options assumed in Merger																		0
Stock options assumed in Merger VALUE																		$ 0
Dividend equivalents, net of forfeitures																		0	$ 0
CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption																						$ 0
Common Class B [Member]
Condensed Financial Statements, Captions [Line Items]
Opening Balance VALUE								$ 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
Net income (loss)																		$ 0	$ 0	$ 0
Stock Granted During Period, Value, Share-based Compensation, Net of Forfeitures																		$ 0
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	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
Realization of tax benefit for dividend equivalent payments VALUE																				$ 0
Net unrealized gain (loss) on derivatives VALUE																		$ 0
Exercise of stock options SHARES																		0	0	0
Exercise of stock options VALUE																		$ 0	$ 0	$ 0
Ending Balance SHARES		4,045,199								7,197,532								4,045,199	7,197,532	7,197,532
Ending Balance VALUE		$ 40,000								$ 72,000								$ 40,000	$ 72,000	$ 72,000
DividendsPreferredStockCash																		0	0	$ 0
Payments Of Dividends																		0	$ 0
Conversion Of Common Class B To Common Classa Value																		$ (32,000)
Conversion Of Stock Shares Converted 2010																		(3,152,333)	0	0
Equity awards assumed in Merger VALUE																		$ 0
StockIssuedDuringPeriodSharesAcquisitions																		0
StockIssuedDuringPeriodValueAcquisitions																		$ 0
Stock options assumed in Merger																		0
Stock options assumed in Merger VALUE																		$ 0
Dividend equivalents, net of forfeitures																		0	$ 0
CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption																						0
Additional Paid In Capital [Member]
Condensed Financial Statements, Captions [Line Items]
Opening Balance VALUE								$ 605,603,000								$ 611,754,000		605,603,000	611,754,000	$ 608,515,000
Net income (loss)																		0	0	29,184,000
Stock Granted During Period, Value, Share-based Compensation, Net of Forfeitures																		0
Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures																		9,546,000	6,528,000	5,517,000
Issuance of common stock related to an incentive plan VALUE																		182,000	379,000	0
Common stock repurchase VALUE																		10,666,000	0	0
Purchase of vested employee restricted stock units																		(2,563,000)	(2,266,000)	(1,561,000)
Forfeitures of dividend equivalents VALUE																				0
Realization of tax benefit for dividend equivalent payments VALUE																				0
Net unrealized gain (loss) on derivatives VALUE																		534,000
Exercise of stock options VALUE																		42,000	264,000	35,000
Ending Balance VALUE		1,737,132,000								605,603,000								1,737,132,000	605,603,000	611,754,000
DividendsPreferredStockCash																		2,574,000	1,788,000	752,000
Payments Of Dividends																		(29,296,000)	(8,666,000)
Conversion Of Common Class B To Common Classa Value																		0
Equity awards assumed in Merger VALUE																		6,771,000
StockIssuedDuringPeriodValueAcquisitions																		1,160,102,000
Stock options assumed in Merger VALUE																		1,007,000
Dividend equivalents, net of forfeitures																		(1,556,000)	(602,000)
CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption																						534,000
Retained Earnings [Member]
Condensed Financial Statements, Captions [Line Items]
Opening Balance VALUE								(212,636,000)								(250,701,000)		(212,636,000)	(250,701,000)	(279,885,000)
Net income (loss)																		233,849,000	38,065,000	29,184,000
Stock Granted During Period, Value, Share-based Compensation, Net of Forfeitures																		0
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
Realization of tax benefit for dividend equivalent payments VALUE																				0
Net unrealized gain (loss) on derivatives VALUE																		4,578,000
Exercise of stock options VALUE																		0	0	0
Ending Balance VALUE		25,791,000								(212,636,000)								25,791,000	(212,636,000)	(250,701,000)
DividendsPreferredStockCash																		0	0	0
Payments Of Dividends																		0	0
Conversion Of Common Class B To Common Classa Value																		0
Equity awards assumed in Merger VALUE																		0
StockIssuedDuringPeriodValueAcquisitions																		0
Stock options assumed in Merger VALUE																		0
Dividend equivalents, net of forfeitures																		0	0
CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption																						4,578,000
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Opening Balance VALUE								393,374,000								361,450,000		393,374,000	361,450,000
Net income (loss)																		233,849,000	38,065,000	29,184,000
Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures																		0	6,539,000	5,524,000
Issuance of common stock related to an incentive plan VALUE																		9,567,000
Purchase of vested employee restricted stock units																		2,565,000	(2,268,000)	(1,562,000)
Forfeitures of dividend equivalents VALUE																		(29,296,000)	(8,666,000)	0
Realization of tax benefit for dividend equivalent payments VALUE																			(1,788)	0
Net unrealized gain (loss) on derivatives VALUE																		(1,556,000)		(752,000)
Exercise of stock options VALUE																		22,000	265,000	35,000
Ending Balance VALUE		$ 1,764,360,000								$ 393,374,000								1,764,360,000	393,374,000	361,450,000	$ 329,021,000
PreferredStockDividendsIncomeStatementImpact																		(2,015,000)	(1,901,000)	$ (752,000)
DividendsPreferredStockCash																		0	(602,000)
Conversion Of Common Class B To Common Classa Value																		0
Equity awards assumed in Merger VALUE																		6,777,000
StockIssuedDuringPeriodValueAcquisitions																		1,161,116,000
Stock options assumed in Merger VALUE																		1,007,000
Dividend equivalents, net of forfeitures																		(1,556,000)
Parent Company [Member] | Common Class A [Member]
Condensed Financial Statements, Captions [Line Items]
Opening Balance VALUE								$ 335,000								$ 325,000		$ 335,000	$ 325,000
Opening Balance SHARES								33,510,184								32,480,551		33,510,184	32,480,551
Stock Issued During Period Shares Restricted Stock Award Net Of Forfeitures																		0	1,095,759	738,195
Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures																		$ 0	$ 11,000	$ 7,000
Stock Issued During Period Shares Employee Stock Purchase Plans																		2,066,241
Issuance of common stock related to an incentive plan VALUE																		$ 21,000
Purchase of vested employee restricted stock units																		$ 9,000	$ (2,000)	$ (1,000)
Purchase of vested employee restricted stock units SHARES																		932,600	(232,297)	(131,688)
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	11,750
Exercise of stock options VALUE																		$ 0	$ 1,000	$ 0
Ending Balance SHARES		139,675,781								33,510,184								139,675,781	33,510,184	32,480,551	31,862,294
Ending Balance VALUE		$ 1,397,000								$ 335,000								$ 1,397,000	$ 335,000	$ 325,000	$ 319,000
Conversion Of Common Class B To Common Classa Value																		$ 32,000
Conversion Of Stock Shares Converted 2010																		3,152,333
Equity awards assumed in Merger VALUE																		$ 6,000
StockIssuedDuringPeriodSharesAcquisitions																		101,407,494
StockIssuedDuringPeriodValueAcquisitions																		$ 1,014,000
Stock options assumed in Merger																		0
Stock options assumed in Merger VALUE																		$ 0
Dividend equivalents, net of forfeitures																		0	0
CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption																						0
Parent Company [Member] | Common Class B [Member]
Condensed Financial Statements, Captions [Line Items]
Opening Balance VALUE								$ 72,000								$ 72,000		$ 72,000	$ 72,000
Opening Balance SHARES								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		4,045,199								7,197,532								4,045,199	7,197,532	7,197,532	7,197,532
Ending Balance VALUE		$ 40,000								$ 72,000								$ 40,000	$ 72,000	$ 72,000	$ 72,000
Conversion Of Common Class B To Common Classa Value																		$ (32,000)
Conversion Of Stock Shares Converted 2010																		(3,152,333)
Equity awards assumed in Merger VALUE																		$ 0
StockIssuedDuringPeriodSharesAcquisitions																		0
StockIssuedDuringPeriodValueAcquisitions																		$ 0
Stock options assumed in Merger																		0
Stock options assumed in Merger VALUE																		$ 0
Dividend equivalents, net of forfeitures																		0	0
CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption																						0
Parent Company [Member] | Additional Paid In Capital [Member]
Condensed Financial Statements, Captions [Line Items]
Opening Balance VALUE								$ 605,603,000								$ 611,754,000		605,603,000	611,754,000
Stock Issued During Period Value Restricted Stock Award Net Of Forfeitures																		0	6,528,000	5,517,000
Issuance of common stock related to an incentive plan VALUE																		9,546,000
Purchase of vested employee restricted stock units																		10,666,000	(2,266,000)	(1,561,000)
Forfeitures of dividend equivalents VALUE																		(29,296,000)	(8,666,000)	0
Realization of tax benefit for dividend equivalent payments VALUE																			1,788	0
Net unrealized gain (loss) on derivatives VALUE																				752,000
Exercise of stock options VALUE																		22,000	264,000	35,000
Ending Balance VALUE		1,737,132,000								605,603,000								1,737,132,000	605,603,000	611,754,000	608,515,000
DividendsPreferredStockCash																		0
Conversion Of Common Class B To Common Classa Value																		0
Equity awards assumed in Merger VALUE																		6,771,000
StockIssuedDuringPeriodValueAcquisitions																		1,160,102,000
Stock options assumed in Merger VALUE																		1,007,000
Dividend equivalents, net of forfeitures																		(1,556,000)	(602,000)
CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption																						534,000
Parent Company [Member] | Retained Earnings [Member]
Condensed Financial Statements, Captions [Line Items]
Opening Balance VALUE								$ (212,636,000)								$ (250,701,000)		(212,636,000)	(250,701,000)
Net income (loss)																		233,849,000	38,065,000	29,184,000
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	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 VALUE																		0	0	0
Ending Balance VALUE		$ 25,791,000								$ (212,636,000)								25,791,000	(212,636,000)	$ (250,701,000)	$ (279,885,000)
Conversion Of Common Class B To Common Classa Value																		0
Equity awards assumed in Merger VALUE																		0
StockIssuedDuringPeriodValueAcquisitions																		0
Stock options assumed in Merger VALUE																		0
Dividend equivalents, net of forfeitures																		$ 0	$ 0
CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption																						$ 4,578,000