GOODWILL, TRADE NAMES, AND OTHER INTANGIBLE ASSETS - Goodwill Rollforward (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2017 USD ($)
Goodwill [Roll Forward]
Goodwill, net of impairment loss, beginning period	$ 79,648
Changes to aggregate goodwill in 2017
Goodwill, net of impairment loss, ending period	123,244
Operating Segments [Member]
Goodwill [Roll Forward]
Aggregate goodwill acquired, beginning period	357,100
Accumulated impairment loss, beginning period	(277,452)
Goodwill, net of impairment loss, beginning period	79,648
Changes to aggregate goodwill in 2017
Goodwill acquired	43,596
Aggregate goodwill acquired, ending period	400,696
Accumulated impairment loss, ending period	(277,452)
Goodwill, net of impairment loss, ending period	123,244
Operating Segments [Member] | Nurse And Allied Staffing [Member]
Goodwill [Roll Forward]
Aggregate goodwill acquired, beginning period	304,277
Accumulated impairment loss, beginning period	(259,732)
Goodwill, net of impairment loss, beginning period	44,545
Changes to aggregate goodwill in 2017
Goodwill acquired	43,596
Aggregate goodwill acquired, ending period	347,873
Accumulated impairment loss, ending period	(259,732)
Goodwill, net of impairment loss, ending period	88,141
Operating Segments [Member] | Physician Staffing [Member]
Goodwill [Roll Forward]
Aggregate goodwill acquired, beginning period	43,405
Accumulated impairment loss, beginning period	(17,720)
Goodwill, net of impairment loss, beginning period	25,685
Changes to aggregate goodwill in 2017
Goodwill acquired	0
Aggregate goodwill acquired, ending period	43,405
Accumulated impairment loss, ending period	(17,720)
Goodwill, net of impairment loss, ending period	25,685
Operating Segments [Member] | Other Human Capital Management Services [Member]
Goodwill [Roll Forward]
Aggregate goodwill acquired, beginning period	9,418
Accumulated impairment loss, beginning period	0
Goodwill, net of impairment loss, beginning period	9,418
Changes to aggregate goodwill in 2017
Goodwill acquired	0
Aggregate goodwill acquired, ending period	9,418
Accumulated impairment loss, ending period	0
Goodwill, net of impairment loss, ending period	$ 9,418