XML 54 R47.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Summary of Movement in Non-Vested Share Options (Detail) - Employee Stock Option - $ / shares | 6 Months Ended
--- | ---
Jun. 30, 2018 | Jun. 30, 2017
Options Outstanding Number of Shares |  |
Beginning Balance (in shares) | 694,727 |
Granted (in shares) | 167,557 |
Vested (in shares) | (316,320) |
Forfeited (in shares) | (2,705) |
Ending Balance (in shares) | 543,259 |
Weighted Average Exercise Price |  |
Beginning balance (USD per share) | $ 68.06 |
Granted (USD per share) | 118.90 |
Vested (USD per share) | 61.76 |
Forfeited (USD per share) | 56.58 |
Ending balance (USD per share) | 87.46 |
Weighted Average Fair Value |  |
Beginning Balance (USD per share) | 20.03 |
Granted (USD per share) | 36.84 | $ 25.06
Vested (USD per share) | 18.41 |
Forfeited (USD per share) | 16.84 |
Ending Balance (USD per share) | $ 26.17 |

X
- Definition Share Based Compensation Arrangement by Share Based Payment Award, Nonvested Options, Forfeited in Period Weighted Average Exercise Price + References No definition available. + Details
Name: | iclr_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonvestedOptionsForfeitedInPeriodWeightedAverageExercisePrice
Namespace Prefix: | iclr_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Share Based Compensation Arrangement by Share Based Payment Award, Nonvested Options, Granted in Period Weighted Average Exercise Price + References No definition available. + Details
Name: | iclr_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonvestedOptionsGrantedInPeriodWeightedAverageExercisePrice
Namespace Prefix: | iclr_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Share Based Compensation Arrangement By Share Based Payment Award Nonvested Options Outstanding Exercise Price Abstract + References No definition available. + Details
Name: | iclr_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonvestedOptionsOutstandingExercisePriceAbstract
Namespace Prefix: | iclr_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Share Based Compensation Arrangement by Share Based Payment Award, Nonvested Options, Outstanding Weighted Average Exercise Price + References No definition available. + Details
Name: | iclr_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonvestedOptionsOutstandingWeightedAverageExercisePrice
Namespace Prefix: | iclr_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Share Based Compensation Arrangement by Share Based Payment Award, Nonvested Options, Vested in Period Weighted Average Exercise Price + References No definition available. + Details
Name: | iclr_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonvestedOptionsVestedInPeriodWeightedAverageExercisePrice
Namespace Prefix: | iclr_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Gross number of share options (or share units) granted during the period. + References No definition available. + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901 + Details
Name: | us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of non-vested options outstanding. + References No definition available. + Details
Name: | us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
Name: | us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfSharesRollForward
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of non-vested options forfeited. + References No definition available. + Details
Name: | us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedOptionsForfeitedNumberOfShares
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Weighted average grant-date fair value of non-vested options forfeited. + References No definition available. + Details
Name: | us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedOptionsForfeitedWeightedAverageGrantDateFairValue
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Weighted average grant-date fair value of non-vested options outstanding. + References No definition available. + Details
Name: | us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

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

X
- Definition Number of options vested. + References No definition available. + Details
Name: | us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Weighted average grant-date fair value of options vested. + References No definition available. + Details
Name: | us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedWeightedAverageGrantDateFairValue
Namespace Prefix: | us-gaap_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_AwardTypeAxis=us-gaap_EmployeeStockOptionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |