CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) (Parenthetical) (USD $) In Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) [Abstract]
Gross billings	$ 2,731	$ 2,354	$ 5,619	$ 4,830
Worksite employee payroll cost	$ 2,258	$ 1,942	$ 4,610	$ 3,960