Fair Value Measurements - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
Jun. 30, 2013
Fair Value Disclosures [Abstract]
Transfers into or out of Level 1, 2 or 3 assets	$ 0

Fair value asset transfer among level one level two level three.

No definition available.

Name:	kfrc_FairValueAssetTransferAmongLevelOneLevelTwoLevelThree
Namespace Prefix:	kfrc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration