2.4.0.82434401 - Disclosure - 12. Fair Value (Details)truefalsefalse1false USDfalsefalse$I2013Q2http://www.sec.gov/CIK0001407739instant2013-06-30T00:00:000001-01-01T00:00:00rateStandardhttp://www.xbrl.org/2009/utrRateutreg0usdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$2false USDfalsefalse$I2012Q4http://www.sec.gov/CIK0001407739instant2012-12-31T00:00:000001-01-01T00:00:00usdStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$1true 3us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]2false 4us-gaap_LongTermDebtus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse725000000725000000USD$falsetruefalse2truefalsefalse707600000707600000USD$falsetruefalsexbrli:monetaryItemTypemonetaryCarrying amount of long-term debt, net of unamortized discount or premium, including current and noncurrent amounts. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 7 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03.16) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.16) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 16 -Article 9 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 20, 22 -Article 5 false2Long-term Debt3false 4us-gaap_LongTermDebtFairValueus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse749000000749000000USD$falsetruefalse2falsefalsefalse00falsefalsefalsexbrli:monetaryItemTypemonetaryThe fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.No definition available.false2Long-term Debt, Fair Value4false 4us-gaap_DebtInstrumentBasisSpreadOnVariableRateus-gaap_truenainstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truetruefalse0.01850.0185falsefalsefalse2falsefalsefalse00falsefalsefalsenum:percentItemTypepureThe percentage points added to the reference rate to compute the variable rate on the debt instrument.No definition available.false0Debt Instrument, Basis Spread on Variable Rate5false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse3false truefalseI2013Q2_us-gaap_LongtermDebtTypeAxis_dft_Acc3Memberhttp://www.sec.gov/CIK0001407739instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseACC3 [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldidft_Acc3Memberus-gaap_LongtermDebtTypeAxisexplicitMemberrateStandardhttp://www.xbrl.org/2009/utrRateutreg0nanafalse0ACC3 [Member]6true 3us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]7false 4us-gaap_DerivativeForwardInterestRateus-gaap_truenainstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truetruefalse0.01450.0145falsefalsefalse2falsefalsefalse00falsefalsefalsenum:percentItemTypepureStated rate on an interest rate forward or futures contract.No definition available.false256Derivative, Forward Interest Rate8false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse4false truefalseI2013Q2_us-gaap_LongtermDebtTypeAxis_us-gaap_LineOfCreditMemberhttp://www.sec.gov/CIK0001407739instant2013-06-30T00:00:000001-01-01T00:00:00falsefalseUnsecured Credit Facility [Member]us-gaap_LongtermDebtTypeAxisxbrldihttp://xbrl.org/2006/xbrldius-gaap_LineOfCreditMemberus-gaap_LongtermDebtTypeAxisexplicitMemberrateStandardhttp://www.xbrl.org/2009/utrRateutreg0nanafalse0Unsecured Credit Facility [Member]9true 3us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]10false 4us-gaap_DerivativeForwardInterestRateus-gaap_truenainstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truetruefalse0.00710.0071falsefalsefalse2falsefalsefalse00falsefalsefalsenum:percentItemTypepureStated rate on an interest rate forward or futures contract.No definition available.false256Derivative, Forward Interest Ratefalse12. Fair Value (Details) (USD $)NoRoundingUnKnownUnKnownUnKnowntruefalsefalseSheethttp://www.dft.com/role/A12FairValueDetails210