EARNINGS PER COMMON SHARE - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Numerator for basic and diluted earnings per share -income available to common shareholders:
Net income	$ 22,568	$ 18,949	$ 42,382	$ 36,570
Denominator for basic earnings per share - weighted average shares	61,194,254	61,115,802	61,115,525	61,064,928
Effect of dilutive securities -
Employee stock awards	763,206	645,680	734,493	606,962
Warrants	69,548	153,812	62,348	152,216
Denominator for diluted earnings per share - adjusted weighted average shares	62,027,008	61,915,294	61,912,366	61,824,106
Basic	$ 0.37	$ 0.31	$ 0.69	$ 0.60
Diluted	$ 0.36	$ 0.31	$ 0.68	$ 0.59

Net Income (Loss) Available to Common Stockholders, Basic and Diluted [Abstract]

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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of call options and warrants using the treasury stock method.

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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

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