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Share-Based Compensation (Details 5) (USD $) | 12 Months Ended |
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Jan. 03, 2015 | Dec. 28, 2013
Options Outstanding |  |
Number Outstanding (in shares) | 1,154,945 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions |
Weighted-Average Remaining Contractual Life | 3 years 8 months 23 days |
Weighted-Average Exercise Price (in dollars per share) | $ 29.93 us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1 |
Options Exercisable |  |
Number Exercisable (in shares) | 737,760 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions |
Weighted-Average Exercise Price (in dollars per share) | $ 33.14 us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1 |
Non-vested Options, Number of Shares |  |
Balance at the beginning of the period (in shares) | 401,678 us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares |
Granted (in shares) | 178,608 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod |
Vested (in shares) | (153,126)us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares |
Forfeited (in shares) | (9,975)us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedOptionsForfeitedNumberOfShares |
Balance at the end of the period (in shares) | 417,185 us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedNumberOfShares |
Non-vested Options, Weighted-Average Fair Value |  |
Balance at the beginning of the period (in dollars per share) | $ 8.16 us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue |
Granted (in dollars per share) | $ 12.24 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue |
Vested (in dollars per share) | $ 9.03 us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedWeightedAverageGrantDateFairValue |
Forfeited (in dollars per share) | $ 8.30 us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedOptionsForfeitedWeightedAverageGrantDateFairValue |
Balance at the end of the period (in dollars per share) | $ 9.98 us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue |
$18.48 |  |
Options Outstanding |  |
Number Outstanding (in shares) | 254,355 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeOneOfExercisePricesMember |
Weighted-Average Remaining Contractual Life | 5 years 10 months 17 days |
Weighted-Average Exercise Price (in dollars per share) | $ 18.48 us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1 / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeOneOfExercisePricesMember | $ 18.48 us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1 / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeOneOfExercisePricesMember
Options Exercisable |  |
Number Exercisable (in shares) | 63,578 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeOneOfExercisePricesMember |
Weighted-Average Exercise Price (in dollars per share) | $ 18.48 us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1 / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeOneOfExercisePricesMember |
$18.49 - 22.81 |  |
Share-based compensation |  |
Exercise price, low end of range (in dollars per share) | $ 18.49 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeTwoOfExercisePricesMember |
Exercise price, high end of range (in dollars per share) | $ 22.81 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeTwoOfExercisePricesMember |
Options Outstanding |  |
Number Outstanding (in shares) | 328,253 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeTwoOfExercisePricesMember |
Weighted-Average Remaining Contractual Life | 3 years 4 months 21 days |
Weighted-Average Exercise Price (in dollars per share) | $ 21.68 us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1 / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeTwoOfExercisePricesMember |
Options Exercisable |  |
Number Exercisable (in shares) | 284,453 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeTwoOfExercisePricesMember |
Weighted-Average Exercise Price (in dollars per share) | $ 21.64 us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1 / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeTwoOfExercisePricesMember |
$22.82 - 29.07 |  |
Share-based compensation |  |
Exercise price, low end of range (in dollars per share) | $ 22.82 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeThreeOfExercisePricesMember |
Exercise price, high end of range (in dollars per share) | $ 29.07 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeThreeOfExercisePricesMember |
Options Outstanding |  |
Number Outstanding (in shares) | 86,665 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeThreeOfExercisePricesMember |
Weighted-Average Remaining Contractual Life | 2 years |
Weighted-Average Exercise Price (in dollars per share) | $ 24.22 us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1 / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeThreeOfExercisePricesMember |
Options Exercisable |  |
Number Exercisable (in shares) | 82,665 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeThreeOfExercisePricesMember |
Weighted-Average Exercise Price (in dollars per share) | $ 24.18 us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1 / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeThreeOfExercisePricesMember |
$29.08 - 32.26 |  |
Share-based compensation |  |
Exercise price, low end of range (in dollars per share) | $ 29.08 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeFourOfExercisePricesMember |
Exercise price, high end of range (in dollars per share) | $ 32.26 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeFourOfExercisePricesMember |
Options Outstanding |  |
Number Outstanding (in shares) | 178,608 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeFourOfExercisePricesMember |
Weighted-Average Remaining Contractual Life | 6 years 11 months 5 days |
Weighted-Average Exercise Price (in dollars per share) | $ 30.97 us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1 / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeFourOfExercisePricesMember |
$32.27 - 48.85 |  |
Share-based compensation |  |
Exercise price, low end of range (in dollars per share) | $ 32.27 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeSixOfExercisePricesMember |
Exercise price, high end of range (in dollars per share) | $ 48.85 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeSixOfExercisePricesMember |
Options Outstanding |  |
Number Outstanding (in shares) | 42,500 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeSixOfExercisePricesMember |
Weighted-Average Remaining Contractual Life | 9 months 15 days |
Weighted-Average Exercise Price (in dollars per share) | $ 42.58 us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1 / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeSixOfExercisePricesMember |
Options Exercisable |  |
Number Exercisable (in shares) | 42,500 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeSixOfExercisePricesMember |
Weighted-Average Exercise Price (in dollars per share) | $ 42.58 us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1 / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeSixOfExercisePricesMember |
$48.86 - 50.00 |  |
Share-based compensation |  |
Exercise price, low end of range (in dollars per share) | $ 48.86 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeSevenOfExercisePricesMember |
Exercise price, high end of range (in dollars per share) | $ 50.00 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeSevenOfExercisePricesMember |
Options Outstanding |  |
Number Outstanding (in shares) | 150,000 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeSevenOfExercisePricesMember |
Weighted-Average Remaining Contractual Life | 1 year 6 months |
Weighted-Average Exercise Price (in dollars per share) | $ 50.00 us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1 / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeSevenOfExercisePricesMember |
Options Exercisable |  |
Number Exercisable (in shares) | 150,000 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeSevenOfExercisePricesMember |
Weighted-Average Exercise Price (in dollars per share) | $ 50.00 us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1 / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeSevenOfExercisePricesMember |
$50.01 - 53.72 |  |
Share-based compensation |  |
Exercise price, low end of range (in dollars per share) | $ 50.01 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeEightOfExercisePricesMember |
Exercise price, high end of range (in dollars per share) | $ 53.72 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeEightOfExercisePricesMember |
Options Outstanding |  |
Number Outstanding (in shares) | 114,564 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeEightOfExercisePricesMember |
Weighted-Average Remaining Contractual Life | 3 months |
Weighted-Average Exercise Price (in dollars per share) | $ 50.73 us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1 / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeEightOfExercisePricesMember |
Options Exercisable |  |
Number Exercisable (in shares) | 114,564 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeEightOfExercisePricesMember |
Weighted-Average Exercise Price (in dollars per share) | $ 50.73 us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1 / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = crai_RangeEightOfExercisePricesMember |

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