Commitments and Contingencies (Details) (USD $)	3 Months Ended		12 Months Ended
	Dec. 31, 2011	Dec. 31, 2011 PENNSYLVANIA [Member] Sales tax contingency [Member]	Dec. 31, 2011 CALIFORNIA [Member] Unemployment tax contingency [Member]	Dec. 31, 2003 CALIFORNIA [Member] Unemployment tax contingency [Member]
Commitments and Contingencies [Abstract]
Disclosure threshold for future non-cancelable purchase and service obligations	Greater than 100,000 and one year
Non-cancelable purchase and service obligations [Abstract]
2012	$ 4,737,000
2013	3,721,000
2014	2,638,000
2015	2,426,000
2016	1,652,000
Thereafter	6,520,000
Total obligations	21,694,000
Pennsylvania Sales Taxes [Abstract]
Adjustment related to the reversal of sales taxes accrued	(2,500,000)	(2,500,000)
Ultimate sales tax that could be incurred on PEO services if defense is not successful		3,000,000
Maximum potential gain related to Pennsylvania sales tax paid in error		2,900,000
California Unemployment Taxes [Abstract]
Unemployment tax reserve account assessment relating to California employees, including penalties and interest			8,100,000	5,600,000
Actual unemployment tax settlement relating to California employees, including penalties and interest			$ 3,100,000