Workers Compensation - Summary of Activities in Liability for Unpaid Claims and Claims Adjustment Expenses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Liability for Unpaid Claims and Claims Adjustment Expense
Liability for unpaid claims and claims adjustment at beginning of period	$ 148,034
Paid related to:
Liability for unpaid claims and claims adjustment at end of period	190,102	$ 148,034
Assets held by or payable to third parties for claim liabilities	(58,522)	(95,372)
Premiums liabilities	9,455	19,820
Other workers compensation assets	(1,012)	(136)
Total net workers compensation liabilities	140,023	72,346
Current portion included in worksite employee-related liability	66,174	36,778
Long term portion	105,481	75,448
Workers compensation liability	171,655	112,226
Current portion included in worksite employee-related asset	2,428	7,975
Long term portion	29,204	31,905
Workers compensation receivable	31,632	39,880
Programs where assets are held by the Company to cover claims liabilities
Liability for Unpaid Claims and Claims Adjustment Expense
Liability for unpaid claims and claims adjustment at beginning of period	92,406	58,610
Incurred related to:
Current year	88,438	61,669
Prior years	4,880	(4,725)
Total incurred	93,318	56,944
Paid related to:
Current year	(16,076)	(11,003)
Prior years	(30,453)	(12,145)
Total paid	(46,529)	(23,148)
Reclassification from workers compensation receivable	5,045	0
Liability for unpaid claims and claims adjustment at end of period	144,240	92,406
Programs where assets are held by third parties to cover claims liabilities
Liability for Unpaid Claims and Claims Adjustment Expense
Liability for unpaid claims and claims adjustment at beginning of period	55,628	62,129
Incurred related to:
Current year	699	1,708
Prior years	21,511	20,126
Total incurred	22,210	21,834
Paid related to:
Current year	(300)	(2,083)
Prior years	(26,631)	(26,252)
Total paid	(26,931)	(28,335)
Reclassification from workers compensation receivable	5,045	0
Liability for unpaid claims and claims adjustment at end of period	$ 45,862	$ 55,628