Segment Information - Reconciliation of Revenue and Segment Operating Income by Reportable Segment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	$ 608,351	$ 535,177	$ 1,210,812	$ 1,067,618
Segment operating income	38,401	45,156	74,144	90,208
Depreciation and amortization	22,071	12,718	42,160	24,428
Depreciation (included in cost of revenue)	355	0	500	0
Share-based compensation	6,347	3,702	11,274	8,888
Interest expense, net, and other	11,443	6,065	22,497	11,738
Income before income taxes	26,958	39,091	51,647	78,470
Technology and Workforce Solutions
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	55,265	24,734	95,538	46,626
Nurse and allied solutions
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	444,464	367,994	868,810	741,466
Physician and leadership solutions
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	108,622	142,449	246,464	279,526
Operating segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	608,351	535,177	1,210,812	1,067,618
Segment operating income	98,339	82,949	187,811	162,760
Operating segments | Technology and Workforce Solutions
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	55,265	24,734	95,538	46,626
Segment operating income	21,839	11,336	37,134	21,719
Operating segments | Nurse and allied solutions
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	444,464	367,994	868,810	741,466
Segment operating income	61,175	52,752	120,783	106,308
Operating segments | Physician and leadership solutions
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	108,622	142,449	246,464	279,526
Segment operating income	15,325	18,861	29,894	34,733
Unallocated corporate overhead
Segment Reporting, Revenue Reconciling Item [Line Items]
Unallocated corporate overhead	$ 31,165	$ 21,373	$ 59,733	$ 39,236