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.

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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	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	$ 216,054	$ 184,004	$ 195,938	$ 166,178
Restricted cash and cash equivalents	14,578	14,569
Restricted cash and available for sale investments	127,715	130,501
Restricted cash and investments, current	139,175	132,115
Payroll funds collected	580,515	825,958
Restricted cash and investments	1,078,037	1,287,147
Cash and Cash Equivalents
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	216,054	184,004
Restricted cash and cash equivalents	14,578	14,569
Restricted cash and available for sale investments	79,540	78,672
Restricted cash and investments, current	136,855	129,795
Payroll funds collected	580,515	825,958
Restricted cash and investments	1,027,542	1,232,998
Available-for-sale Securities
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash and available for sale investments	48,175	51,829
Restricted cash and investments	48,175	51,829
Certificates of deposit
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash and investments, current	2,320	2,320
Restricted cash and investments	2,320	2,320
Health Benefit Claims Collateral
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash and investments, current	68,906	65,022
Health Benefit Claims Collateral \| Cash and Cash Equivalents
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash and investments, current	68,906	65,022
Workers' Compensation Claims Collateral
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash and investments, current	67,949	64,773
Workers' Compensation Claims Collateral \| Cash and Cash Equivalents
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash and investments, current	67,949	64,773
Investment Type Collateral
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash and investments, current	$ 2,320	$ 2,320