STOCK COMPENSATION PLANS (Details) (USD $)	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010	Dec. 31, 2009
STOCK COMPENSATION PLANS
Reduction in income before income taxes resulting from incremental stock based compensation expense	$ 685,000		$ 937,000	$ 1,400,000
Reduction in net income resulting from incremental stock based compensation expense	397,000		544,000	841,000
Reduction in basic earnings per share resulting from incremental stock based compensation expense (in dollars per share)	$ 0.00		$ 0.00	$ 0.01
Reduction in diluted earnings per share resulting from incremental stock based compensation expense (in dollars per share)	$ 0.00		$ 0.00	$ 0.01
Total compensation expense related to stock options and restricted stock awards, before taxes	13,500,000		8,500,000	5,300,000
Total compensation expense related to stock options and restricted stock awards, net income	7,900,000		4,900,000	3,100,000
Net tax benefit (provision) recognized in equity for stock compensation plans	717,000		(170,000)
Incentive shares available to be issued (in shares)	4,648,828
Stock Options
Summary of Stock-based Compensation Plans
Vesting period, minimum (in years)	P3Y
Vesting period, maximum (in years)	P4Y
Summary of stock option activity
Outstanding at beginning of year (in shares)	1,438,979
Granted (in shares)	8,654
Exercised (in shares)	(330,756)
Forfeited (in shares)	(171,797)
Outstanding at end of year (in shares)	945,080		1,438,979
Vested or expected to vest at year-end (in shares)	933,258
Exercisable at year-end (in shares)	758,166
Outstanding at beginning of year, weighted average exercise price (in dollars per share)	$ 24.21
Granted, weighted average exercise price (in dollars per share)	$ 23.11
Exercised, weighted average exercise price (in dollars per share)	$ 12.70
Forfeited, weighted average exercise price (in dollars per share)	$ 29.92
Outstanding at end of year, weighted average exercise price (in dollars per share)	$ 27.19		$ 24.21
Vested or expected to vest at year-end, weighted average exercise price (in dollars per share)	$ 27.30
Exercisable at year-end, weighted average exercise price (in dollars per share)	$ 29.34
Outstanding at end of year, weighted average remaining term (in years)	2.28
Vested or expected to vest at year-end, weighted average remaining term (in years)	2.26
Exercisable at year-end, weighted average remaining term (in years)	1.98
Outstanding at end of year, aggregate intrinsic value	782,000
Vested or expected to vest at year-end, aggregate intrinsic value	739,000
Exercisable at year-end, aggregate intrinsic value	350,000
Summary of unvested stock option activity
Unvested options at beginning of period, weighted average grant date fair value (in shares)	416,851
Granted, weighted average grant date fair value (in shares)	8,654
Vested, weighted average grant date fair value (in shares)	(227,813)
Forfeited, weighted average grant date fair value (in shares)	(10,778)
Unvested options at end of period, weighted average grant date fair value (in shares)	186,914		416,851
Unvested options at beginning of period (in dollars per share)	$ 5.04
Granted (in dollars per share)	$ 13.21	[1]		$ 3.00	[1]
Vested (in dollars per share)	$ 5.59
Forfeited (in dollars per share)	$ 4.56
Unvested options at ending of period (in dollars per share)	$ 4.77		$ 5.04
Fair value assumptions under the Black-Scholes option pricing model
Fair value assumptions, method used	Black-Scholes option-pricing model			Black-Scholes option-pricing model
Expected term (in years)	4	[2]		4	[2]
Expected volatility (as a percent)	78.10%	[3]		60.50%	[3]
Expected dividend yield (as a percent)	0.20%	[4]		0.60%	[4]
Risk-free interest rate (as a percent)	1.60%	[5]		1.80%	[5]
Share based compensation plan, additional disclosures
Cash proceeds from stock option exercises	4,200,000		3,600,000
Weighted average grant date fair value of stock options granted during the year (in dollars per share)	$ 13.21	[1]		$ 3.00	[1]
Total intrinsic value of options exercised	2,650,000		1,772,000	53,000
Total fair value of options vested	1,274,000		2,137,000	1,638,000
Total unrecognized stock compensation expense	185,000
Weighted average period to recognize unrecognized compensation cost (in years)	2.8
Stock Options | Maximum
Summary of Stock-based Compensation Plans
Contractual term of stock option grants (in years)	P10Y
Stock Options | Minimum
Summary of Stock-based Compensation Plans
Contractual term of stock option grants (in years)	P7Y
Restricted Stock
Summary of Stock-based Compensation Plans
Vesting period, minimum (in years)	P1Y
Vesting period, maximum (in years)	P5Y
Time-based restricted stock awards
Share based compensation plan, additional disclosures
Total unrecognized stock compensation expense	16,500,000
Weighted average period to recognize unrecognized compensation cost (in years)	2.13
Total fair value of restricted stock awards vested	4,900,000		4,300,000	1,000,000
Summary of restricted stock activity
Outstanding unvested at beginning of year (in shares)	1,789,498
Granted (in shares)	502,781
Vested (in shares)	(242,025)
Forfeited (in shares)	(240,193)
Outstanding unvested at end of year (in shares)	1,810,061		1,789,498
Outstanding unvested at beginning of year, weighted average price (in dollars per share)	$ 17.09
Granted, weighted average price (in dollars per share)	$ 19.17		$ 17.11	$ 7.14
Vested, weighted average price (in dollars per share)	$ 23.82
Forfeited, weighted average price (in dollars per share)	$ 17.05
Outstanding unvested at end of year, weighted average price (in dollars per share)	$ 16.77		$ 17.09
Performance-based restricted stock awards
Share based compensation plan, additional disclosures
Total unrecognized stock compensation expense	7,400,000
Weighted average period to recognize unrecognized compensation cost (in years)	1.88
Summary of restricted stock activity
Granted (in shares)	513,022
Forfeited (in shares)	(32,287)
Outstanding unvested at end of year (in shares)	480,735
Granted, weighted average price (in dollars per share)	$ 22.25
Forfeited, weighted average price (in dollars per share)	$ 23.11
Outstanding unvested at end of year, weighted average price (in dollars per share)	$ 22.19
Stock Purchase Plan
Stock purchase plan
Purchase price of shares in terms compared to market price per share (as a percent)	90.00%
Common stock, shares authorized (in shares)	2,000,000
Shares sold to employees under purchase plan (in shares)	64,032		56,448
Value of shares sold to employees under purchase plan	25,000
Stock Issued During Period, Value, Employee Stock Purchase Plan	$ 1,000,000		$ 849,000

[1] The Company did not issue any stock options during the year ended December 31, 2010.

[2] The expected term (estimated period of time outstanding) of stock options granted was estimated using the historical exercise behavior of employees.

[3] The expected volatility was based on historical volatility for a period equal to the stock option's expected term.

[4] The expected dividend yield is based on the Company's prevailing dividend rate at the time of grant.

[5] The risk-free rate is based on the U.S. Treasury strips in effect at the time of grant equal to the stock option's expected term.