Segment Data - Operating Segments (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenues from services	$ 628,218	$ 636,098	$ 753,561	$ 788,732	$ 640,679	$ 374,905	$ 331,827	$ 329,241	$ 2,806,609	$ 1,676,652	$ 836,417
Contribution income									360,955	210,066	77,788
Corporate overhead									67,087	55,142	51,900
Depreciation and amortization									12,576	9,852	12,671
Acquisition and integration-related costs									726	1,068	77
Restructuring costs	$ 0	$ 2,500		$ 0	$ 0	$ 0	$ 800	$ 1,200	1,861	2,630	6,052
Impairment charges									5,597	2,070	16,248
Income (loss) from operations									273,108	139,304	(9,160)
Nurse And Allied Staffing
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenues from services									2,700,383	1,605,781	768,483
Contribution income									355,447	205,738	74,169
Physician Staffing
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Revenues from services									106,226	70,871	67,934
Contribution income									$ 5,508	$ 4,328	$ 3,619