FINANCING ARRANGEMENTS (Details) (USD $)			1 Months Ended	6 Months Ended			1 Months Ended								6 Months Ended
	Jun. 30, 2011	Dec. 31, 2010	Mar. 31, 2011 Senior secured notes	Jun. 30, 2011 Senior secured notes	Dec. 31, 2010 Senior secured notes	May 31, 2011 Revolving credit facility	May 31, 2011 Revolving credit facility Canadian subsidiaries	Jun. 30, 2011 Revolving credit facility LIBOR loans	Jun. 30, 2011 Revolving credit facility Base rate loans	May 31, 2011 Letters of credit	May 31, 2011 Letters of credit Canadian subsidiaries	May 31, 2011 Previous revolving credit facility	Jun. 30, 2011 Previous revolving credit facility LIBOR loans	Jun. 30, 2011 Previous revolving credit facility Base rate loans	Jun. 30, 2011 LIBOR loans	Jun. 30, 2011 Base rate loans
Financing arrangements
Senior secured notes, at 7.625%, due on August 15, 2016				$ 520,000,000	$ 270,000,000
Senior secured notes, interest rate (as a percent)				7.625%	7.625%
Unamortized notes premium and discount, net	4,994,000	(5,993,000)
Long-term obligations	524,994,000	264,007,000
Revolving credit facility, maximum borrowing capacity						150,000,000	100,000,000			140,000,000	75,000,000	120,000,000
Senior secured notes issued, aggregate principal amount			250,000,000
Purchase price of debt instrument under purchase agreement (as a percent)				104.50%
Effective yield to maturity on debt instrument (as a percent)				6.132%
Net proceeds from issuance and sale of new notes, after deducting initial purchasers' discount and estimated other transaction expenses				255,600,000
Fair-value of outstanding long-term debt				$ 538,300,000	$ 278,300,000
2012 redemption price as a percentage of the principle amount (as a percent)				103.813%
2013 redemption price as a percentage of the principle amount (as a percent)				101.906%
2014 and thereafter redemption price as a percentage of the principle amount (as a percent)				100.00%
Maximum percentage of the aggregate principal amount of notes redeemable on or after September 29, 2011 but prior to August 15, 2012 (as a percent)				10.00%
Redemption price as a percentage of principal amount of notes redeemable on or after September 29, 2011 but prior to August 15, 2012 (as a percent)				103.00%
Maximum percentage of the aggregate principal amount of notes redeemable prior to August 15, 2012 with net proceeds of certain equity offerings (as a percent)				35.00%
Percentage of redemption price to principle amount (as a percent)				107.625%
Percentage of principal amount at which the entity may redeem some or all of the notes prior to April 1, 2013 (as a percent)				100.00%
Percentage of principal amount at which notes may be required to be repurchased in event of change of control (as a percent)				101.00%
Percentage of principal amount at which notes may be required to be repurchased in event of sale of assets under specified circumstances (as a percent)				100.00%
Maximum number of days following issuance of debt in which the exchange offer is to be consummated (in days)				180
Maximum number of days to declare shelf registration statement effective from the date of specific events (in days)				90
Special interest on default of registration obligations under the registration rights agreement				1.00%
Number of subsidiaries to be added as a party to the facility							1
Variable interest rate, basis															LIBOR	BofA's base rate
Applicable margin on variable interest rate basis, low end of range (as a percent)								1.75%	0.75%				2.25%	1.25%
Applicable margin on variable interest rate basis, high end of range (as a percent)								2.25%	1.25%				2.75%	1.75%