XML 38 R26.htm IDEA: XBRL DOCUMENT
v3.20.2

Leases Related Party Leases (Details) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2020 USD ($) property | Jun. 30, 2019 USD ($) | Jun. 30, 2020 USD ($) property | Jun. 30, 2019 USD ($)
Related Party Transactions [Abstract] |  |  |  |
Number of Leased Properties Owned by Related Parties | property | 2 |  | 2 |
Costs and Expenses, Related Party | $ | $ 0.2 | $ 0.3 | $ 0.4 | $ 0.6

X
- Definition Number of Leased Properties Owned by Related Parties + References No definition available. + Details
Name: | asgn_NumberOfLeasedPropertiesOwnedByRelatedParties
Namespace Prefix: | asgn_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Costs of sales and operating expenses for the period incurred from transactions with related parties. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.2) -URI http://asc.fasb.org/extlink&oid=120395209&loc=SL114868664-224227 + Details
Name: | us-gaap_CostsAndExpensesRelatedParty
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_RelatedPartyTransactionsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration