INCOME TAXES (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Income before income taxes
Domestic	$ 389,459	$ 372,669	$ 206,971
Foreign	18,010	7,615	633
Income before income taxes	407,469	380,284	207,604
Current:
Federal	120,137	117,332	63,130
State	15,433	21,099	13,371
Foreign	8,656	5,022	4,091
Total	144,226	143,453	80,592
Deferred:
Federal	(363)	(2,238)	(3,310)
State	(955)	(1,222)	(1,351)
Foreign	(460)	95	(660)
Total	(1,778)	(3,365)	(5,321)
Income tax expense	142,448	140,088	75,271
Percent of pretax earnings:
Statutory federal tax rate (as a percent)	35.00%	35.00%	35.00%
Increase (reduction) resulting from, State income tax, net of federal tax benefit (as a percent)	3.10%	3.20%	3.00%
Increase (reduction) resulting from, Other permanent differences (as a percent)	0.10%	0.60%	2.00%
Increase (reduction) resulting from, International operations, net of foreign tax credits (as a percent)	0.00%	(0.10%)	(1.60%)
Increase (reduction) resulting from, Federal tax credits and income deductions (as a percent)	(2.10%)	(2.10%)	(2.40%)
Increase (reduction) resulting from, Tax impact of uncertain tax positions and other (as a percent)	(1.10%)	0.20%	0.30%
Effective income tax rate (as a percent)	35.00%	36.80%	36.30%
Current assets:
Operating reserves	3,345	4,507
Deferred revenue	2,871	2,377
Accrued worker compensation	2,562	2,436
Other assets	3,790	3,028
Total current assets	12,568	12,348
Current liabilities:
Prepaid expenses	(5,699)	(3,901)
Other liabilities	(3,051)	(3,182)
Total current liabilities	(8,750)	(7,083)
Current assets (liabilities):
Operating reserves	3,345	4,507
Deferred revenue	2,871	2,377
Prepaid expenses	(5,699)	(3,901)
Accrued worker compensation	2,562	2,436
Other net	739	(154)
Total current	3,818	5,265
Non-current assets:
Fixed assets	17,410	14,809
Stock compensation	3,111	2,711
Net operating loss carryforwards	6,763	7,020
Long-term rent liabilities	9,766	8,141
Other assets	5,744	4,310
Valuation allowance	(565)	(1,765)
Total non-current assets	42,229	35,226
Non-current liabilities:
Intangibles	(324,606)	(318,429)
Total non-current liabilities	(324,606)	(318,429)
Non-current assets (liabilities):
Intangibles	(324,606)	(318,429)
Fixed assets	17,410	14,809
Stock compensation	3,111	2,711
Net operating loss carryforwards	6,763	7,020
Long-term rent liabilities	9,766	8,141
Other	5,744	4,310
Valuation allowance	(565)	(1,765)
Total non-current	(282,377)	(283,203)
Total deferred tax assets	54,797	47,574
Total Deferred tax liabilities	(333,356)	(325,512)
Total net deferred taxes	$ (278,559)	$ (277,938)