XML 30 R24.htm IDEA: XBRL DOCUMENT v2.4.1.9
Marketable Securities (Details) (USD $)
In Thousands, unless otherwise specified
3 Months Ended
Mar. 31, 2015
Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]    
Document Period End Date Mar. 31, 2015  
Amortized Cost $ 171,926us-gaap_AvailableForSaleSecuritiesAmortizedCost $ 184,796us-gaap_AvailableForSaleSecuritiesAmortizedCost
Unrealized Gains 13us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax 5us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
Unrealized Losses (10)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax (44)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
Fair Value 171,929us-gaap_AvailableForSaleSecurities 184,757us-gaap_AvailableForSaleSecurities
Included in cash and cash equivalents [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 13,199us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_BalanceSheetLocationAxis
= us-gaap_CashAndCashEquivalentsMember
3,480us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_BalanceSheetLocationAxis
= us-gaap_CashAndCashEquivalentsMember
Unrealized Gains 0us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
/ us-gaap_BalanceSheetLocationAxis
= us-gaap_CashAndCashEquivalentsMember
0us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
/ us-gaap_BalanceSheetLocationAxis
= us-gaap_CashAndCashEquivalentsMember
Unrealized Losses 0us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_BalanceSheetLocationAxis
= us-gaap_CashAndCashEquivalentsMember
0us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_BalanceSheetLocationAxis
= us-gaap_CashAndCashEquivalentsMember
Fair Value 13,199us-gaap_AvailableForSaleSecurities
/ us-gaap_BalanceSheetLocationAxis
= us-gaap_CashAndCashEquivalentsMember
3,480us-gaap_AvailableForSaleSecurities
/ us-gaap_BalanceSheetLocationAxis
= us-gaap_CashAndCashEquivalentsMember
Included in marketable securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 158,727us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_BalanceSheetLocationAxis
= cslt_MarketableSecuritiesMember
175,093us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_BalanceSheetLocationAxis
= cslt_MarketableSecuritiesMember
Unrealized Gains 13us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
/ us-gaap_BalanceSheetLocationAxis
= cslt_MarketableSecuritiesMember
5us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
/ us-gaap_BalanceSheetLocationAxis
= cslt_MarketableSecuritiesMember
Unrealized Losses (10)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_BalanceSheetLocationAxis
= cslt_MarketableSecuritiesMember
(41)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_BalanceSheetLocationAxis
= cslt_MarketableSecuritiesMember
Fair Value 158,730us-gaap_AvailableForSaleSecurities
/ us-gaap_BalanceSheetLocationAxis
= cslt_MarketableSecuritiesMember
175,057us-gaap_AvailableForSaleSecurities
/ us-gaap_BalanceSheetLocationAxis
= cslt_MarketableSecuritiesMember
Included in marketable securities, noncurrent [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost   6,223us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_BalanceSheetLocationAxis
= cslt_MarketableSecuritiesNoncurrentMember
Unrealized Gains   0us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
/ us-gaap_BalanceSheetLocationAxis
= cslt_MarketableSecuritiesNoncurrentMember
Unrealized Losses   (3)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_BalanceSheetLocationAxis
= cslt_MarketableSecuritiesNoncurrentMember
Fair Value   6,220us-gaap_AvailableForSaleSecurities
/ us-gaap_BalanceSheetLocationAxis
= cslt_MarketableSecuritiesNoncurrentMember
U.S. agency obligations [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 153,201us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
177,297us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Unrealized Gains 12us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
4us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Unrealized Losses (10)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
(44)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Fair Value 153,203us-gaap_AvailableForSaleSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
177,257us-gaap_AvailableForSaleSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
U.S. treasury securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 5,526us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USTreasurySecuritiesMember
5,580us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USTreasurySecuritiesMember
Unrealized Gains 1us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USTreasurySecuritiesMember
1us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USTreasurySecuritiesMember
Unrealized Losses 0us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USTreasurySecuritiesMember
0us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USTreasurySecuritiesMember
Fair Value 5,527us-gaap_AvailableForSaleSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USTreasurySecuritiesMember
5,581us-gaap_AvailableForSaleSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USTreasurySecuritiesMember
Money market mutual funds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 13,199us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MoneyMarketFundsMember
1,919us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MoneyMarketFundsMember
Unrealized Gains 0us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MoneyMarketFundsMember
0us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MoneyMarketFundsMember
Unrealized Losses 0us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MoneyMarketFundsMember
0us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MoneyMarketFundsMember
Fair Value $ 13,199us-gaap_AvailableForSaleSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MoneyMarketFundsMember
$ 1,919us-gaap_AvailableForSaleSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MoneyMarketFundsMember