RECEIVABLES, CONTRACT ASSETS, AND DEFERRED REVENUE - Summary of Unbilled Receivables (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Receivables [Abstract]
1 year or less	$ 169,554	$ 172,656
1-2 years	79,128
2-5 years	38,761
Total	$ 287,443
Percentage of unbilled receivables, 1 Year or Less	59.00%
Percentage of unbilled receivables, 1-2 Years	28.00%
Percentage of unbilled receivables, 2-5 Years	13.00%
Total percentage of unbilled receivables	100.00%

Unbilled Receivables Current and Non Current

No definition available.

Name:	pega_UnbilledReceivablesCurrentAndNonCurrent
Namespace Prefix:	pega_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Unbilled receivables current and non current percentage.

+ References

No definition available.

+ Details

Name:	pega_UnbilledReceivablesCurrentAndNonCurrentPercentage
Namespace Prefix:	pega_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Unbilled receivables not billable at balance sheet date amount expected to be collected within year one and two.

+ References

No definition available.

+ Details

Name:	pega_UnbilledReceivablesNotBillableAtBalanceSheetDateAmountExpectedToBeCollectedWithinYearOneAndTwo
Namespace Prefix:	pega_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Unbilled receivables not billable at balance sheet date amount expected to be collected within year two and five.

+ References

No definition available.

+ Details

Name:	pega_UnbilledReceivablesNotBillableAtBalanceSheetDateAmountExpectedToBeCollectedWithinYearTwoAndFive
Namespace Prefix:	pega_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Unbilled receivables not billable at balance sheet date expected percentage to be collected within one year.

+ References

No definition available.

+ Details

Name:	pega_UnbilledReceivablesNotBillableAtBalanceSheetDateExpectedPercentageToBeCollectedWithinOneYear
Namespace Prefix:	pega_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Unbilled receivables not billable at balance sheet date expected percentage to be collected within year one and two.

+ References

No definition available.

+ Details

Name:	pega_UnbilledReceivablesNotBillableAtBalanceSheetDateExpectedPercentageToBeCollectedWithinYearOneAndTwo
Namespace Prefix:	pega_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Unbilled receivables not billable at balance sheet date expected percentage to be collected within year two and five.

+ References

No definition available.

+ Details

Name:	pega_UnbilledReceivablesNotBillableAtBalanceSheetDateExpectedPercentageToBeCollectedWithinYearTwoAndFive
Namespace Prefix:	pega_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_ReceivablesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount received for services rendered and products shipped, but not yet billed, for non-contractual agreements due within one year or the normal operating cycle, if longer.

+ References

No definition available.

+ Details

Name:	us-gaap_UnbilledReceivablesCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant