EARNINGS PER COMMON SHARE - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2016
Sep. 30, 2015
Sep. 30, 2016
Sep. 30, 2015
Numerator for basic and diluted earnings per share -income available to common shareholders:        
Net income $ 22,850 $ 18,673 $ 65,232 $ 55,243
Denominator for basic earnings per share - weighted average shares 61,280,283 61,135,749 61,170,845 61,088,794
Effect of dilutive securities -        
Employee stock awards 740,977 715,585 736,659 643,536
Warrants 64,807 136,461 55,457 126,394
Denominator for diluted earnings per share - adjusted weighted average shares 62,086,067 61,987,795 61,962,961 61,858,724
Basic $ 0.37 $ 0.31 $ 1.07 $ 0.90
Diluted $ 0.37 $ 0.30 $ 1.05 $ 0.89