SHARE-BASED COMPENSATION Outstanding Stock Options (Detail) (USD $)					12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2012 $5.00	Dec. 31, 2012 $5.50	Dec. 31, 2012 $6.90 - $7.66	Dec. 31, 2012 $7.96 - $8.14	Dec. 31, 2012 $9.17 - $10.98	Dec. 31, 2012 $11.18 - $11.49	Dec. 31, 2012 $12.28 - $12.65	Dec. 31, 2012 $12.65 - $14.57
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price, Lower Limit (in dollars per share)							$ 6.90	$ 7.96	$ 9.17	$ 11.18	$ 12.28	$ 12.69
Exercise Price, Upper Limit (in dollars per share)					$ 5.00	$ 5.50	$ 7.66	$ 8.14	$ 10.98	$ 11.99	$ 12.65	$ 14.57
Options Outstanding (in shares)	3,186,414	2,238,673	1,732,962	1,032,250	109,950	752,725	384,386	92,274	415,205	176,350	121,274	1,134,250
Options Outstanding, Intrinsic value	$ 10,166,081				$ 845,515	$ 5,412,093	$ 2,025,213	$ 433,819	$ 1,249,234	$ 170,430	$ 29,777	$ 0
Options Vested (in shares)	1,543,284				94,250	645,378	36,820	42,045	219,658	108,924	68,517	327,692
Options vested, Intrinsic Value	$ 6,561,355				$ 724,783	$ 4,640,268	$ 194,467	$ 198,213	$ 690,737	$ 98,292	$ 14,595	$ 0
Weighted Average Remaining Life					5 years 9 months 19 days	6 years 9 months 29 days	9 years 26 days	8 years 10 months 24 days	8 years 1 month 20 days	8 years 2 months 23 days	8 years 2 months 20 days	9 years 2 months 13 days