Funds collected to cover worksite employee related liabilities.

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Cash
-URI http://asc.fasb.org/extlink&oid=6506951

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=28358313&loc=d3e6676-107765

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3044-108585

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Cash Equivalents
-URI http://asc.fasb.org/extlink&oid=6507016

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.1)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

The carrying amounts of cash and cash equivalent items which are restricted as to withdrawal or usage. Restrictions may include legally restricted deposits held as compensating balances against short-term borrowing arrangements, contracts entered into with others, or entity statements of intention with regard to particular deposits; however, time deposits and short-term certificates of deposit are not generally included in legally restricted deposits. Excludes compensating balance arrangements that are not agreements which legally restrict the use of cash amounts shown on the balance sheet. For a classified balance sheet represents the current portion only (the noncurrent portion has a separate concept); there is a separate and distinct element for unclassified presentations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.1)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Cash and investments whose use in whole or in part is restricted for the long-term, generally by contractual agreements or regulatory requirements. For use in an unclassified balance sheet.

+ References

No definition available.

+ Details

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- Definition

The current cash, cash equivalents and investments that are restricted as to withdrawal or usage. Restrictions may include legally restricted deposits held as compensating balances against short-term borrowing arrangements, contracts entered into with others, or entity statements of intention with regard to particular deposits; however, time deposits and short-term certificates of deposit are not generally included in legally restricted deposits. Excludes compensating balance arrangements that are not agreements which legally restrict the use of cash amounts shown on the balance sheet. Includes current cash equivalents and investments that are similarly restricted as to withdrawal, usage or disposal.

+ References

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- Definition

The noncurrent cash, cash equivalents and investments that is restricted as to withdrawal or usage. Restrictions may include legally restricted deposits held as compensating balances against borrowing arrangements, contracts entered into with others, or entity statements of intention with regard to particular deposits classified as long-term; that is not expected to be released from such existing restrictions within one year of the balance sheet date or operating cycle, whichever is longer. Excludes compensating balance arrangements that are not agreements which legally restrict the use of cash amounts shown on the balance sheet. Includes noncurrent cash equivalents and investments that are similarly restricted as to withdrawal, usage or disposal.

+ References

No definition available.

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Cash, Cash Equivalents and Investments - Components of Cash, Cash Equivalents and Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	$ 184,004	$ 166,178	$ 134,341	$ 94,356
Restricted cash and cash equivalents	14,569	14,557
Restricted cash and investments, noncurrent	130,501	101,806
Restricted cash and investments, current	132,115	96,736
Payroll funds collected	825,958	859,322
Restricted cash and investments	1,287,147	1,238,599
Cash and cash equivalents
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	184,004	166,178
Restricted cash and cash equivalents	14,569	14,557
Restricted cash and investments, noncurrent	78,672	38,711
Restricted cash and investments, current	129,795	92,917
Payroll funds collected	825,958	859,322
Restricted cash and investments	1,232,998	1,171,685
Available for sale marketable securities
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash and investments, noncurrent	51,829	63,095
Restricted cash and investments, current	0	1,500
Restricted cash and investments	51,829	64,595
Certificate of deposits
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash and investments, current	2,320	2,319
Restricted cash and investments	2,320	2,319
Health Benefit Claims
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash and investments, current	65,022	46,980
Health Benefit Claims \| Cash and cash equivalents
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash and investments, current	65,022	46,980
Workers' Compensation Claims
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash and investments, current	64,773	47,437
Workers' Compensation Claims \| Cash and cash equivalents
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash and investments, current	64,773	45,937
Workers' Compensation Claims \| Available for sale marketable securities
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash and investments, current		1,500
Investment Type Collateral
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash and investments, current	$ 2,320	$ 2,319