EARNINGS PER SHARE (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Numerator for earnings per share:
Net income	$ 18,759		$ 16,437		$ 14,118		$ 12,680		$ 14,999		$ 14,065		$ 13,321		$ 12,099		$ 61,994		$ 54,484		$ 44,353
Numerator for basic earnings per share																	61,994		51,143		11,765
Denominator for basic earnings per share:
Weighted average common shares outstanding (in shares)																	45,754		40,190		17,094
Denominator for diluted (common) earnings per share (in shares)																	48,358		43,821		20,473
Denominator for basic and diluted earnings per share:
Weighted average puttable common shares outstanding (in shares)																	0		0		18
Earnings per share
Basic (in dollars per share)	$ 0.40	[1]	$ 0.36	[1]	$ 0.31	[1]	$ 0.28	[1]	$ 0.35	[1]	$ 0.33	[1]	$ 0.31	[1]	$ 0.30	[1]	$ 1.35	[1]	$ 1.27	[1]
Diluted (in dollars per share)	$ 0.38	[1]	$ 0.34	[1]	$ 0.29	[1]	$ 0.27	[1]	$ 0.32	[1]	$ 0.30	[1]	$ 0.29	[1]	$ 0.27	[1]	$ 1.28	[1]	$ 1.17	[1]
Excluded Options due to Anti-Dilutive (in shares)																	1,080		1,534		572
Stock Options [Member]
Denominator for basic earnings per share:
Effect of dilutive securities (in shares)																	2,604		3,631		3,379
Common Stock [Member]
Numerator for earnings per share:
Net income																	61,994		54,484		44,353
Accretion of preferred stock																	0		0		(17,563)
Net income allocated to participating securities																	0		(3,341)		(15,025)
Effect on income available from redemption of preferred stock																	0		0		0
Numerator for basic earnings per share																	61,994		51,143		11,765
Effect on income available from reallocation of options																	0		261		1,185
Numerator for diluted earnings per share																	61,994		51,404		12,950
Denominator for basic earnings per share:
Weighted average common shares outstanding (in shares)																	45,754,000		40,190,000		17,094,000
Denominator for diluted (common) earnings per share (in shares)																	48,358,000		43,821,000		20,473,000
Earnings per share
Basic (in dollars per share)																	$ 1.35		$ 1.27		$ 0.69
Diluted (in dollars per share)																	$ 1.28		$ 1.17		$ 0.63
Puttable Common Stock [Member]
Numerator for earnings per share:
Numerator for basic earnings per share																	0		0		26
Effect on income available from reallocation of options																	0		0		(12)
Numerator for diluted earnings per share																	$ 0		$ 0		$ 14
Denominator for basic earnings per share:
Weighted average common shares outstanding (in shares)																	0		0		18,000
Denominator for diluted (common) earnings per share (in shares)																	0		0		18,000
Earnings per share
Basic (in dollars per share)																	$ 0		$ 0		$ 1.42
Diluted (in dollars per share)																	$ 0		$ 0		$ 0.77

[1] Earnings per share amounts for each quarter may not necessarily total to the yearly earnings per share due to the weighting of shares outstanding on a quarterly and year-to-date basis.