Segment Information (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($) segment	Sep. 30, 2014 USD ($)
Segment Reporting [Abstract]
Reportable business segments | segment			3
Schedule of reconciliation of revenue and segment operating income by reportable segment to consolidated results
Revenue	$ 382,859	$ 264,584	$ 1,060,513	$ 756,378
Operating Income	37,607	15,901	92,551	48,952
Depreciation and amortization	5,304	4,086	15,631	11,916
Share-based compensation	2,021	1,791	6,551	5,361
Interest expense, net (including loss on debt extinguishment of $3,113 for the nine months ended September 30, 2014), and other	2,013	1,433	5,797	7,908
Income before income taxes	35,594	14,468	86,754	41,044
Loss on debt extinguishment		0	0	3,113
Operating segments [Member]
Schedule of reconciliation of revenue and segment operating income by reportable segment to consolidated results
Revenue	382,859	264,584	1,060,513	756,378
Operating Income	58,749	32,174	153,414	93,187
Operating segments [Member] | Nurse and allied healthcare staffing [Member]
Schedule of reconciliation of revenue and segment operating income by reportable segment to consolidated results
Revenue	266,279	174,292	735,341	503,636
Operating Income	40,873	21,279	108,169	63,283
Operating segments [Member] | Locum tenens staffing [Member]
Schedule of reconciliation of revenue and segment operating income by reportable segment to consolidated results
Revenue	101,755	78,816	285,835	219,996
Operating Income	13,321	8,139	34,142	22,830
Operating segments [Member] | Physician permanent placement services [Member]
Schedule of reconciliation of revenue and segment operating income by reportable segment to consolidated results
Revenue	14,825	11,476	39,337	32,746
Operating Income	4,555	2,756	11,103	7,074
Corporate, non-segment [Member]
Schedule of reconciliation of revenue and segment operating income by reportable segment to consolidated results
Unallocated corporate overhead	$ 13,817	$ 10,396	$ 38,681	$ 26,958