2.4.0.81132 - Disclosure - Pension and Other Postretirement Healthcare Benefits - Summary of Expected Benefit Payments (Detail)truefalseIn Millions, unless otherwise specifiedfalse1false USDfalsefalse$eol_PE864322--13S-4-0005_STD_0_20121231_0http://www.sec.gov/CIK0001530804instant2012-12-31T00:00:000001-01-01T00:00:00iso4217_USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$1true 3us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]2false 4us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonthsus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse2900000029USD$falsetruefalsexbrli:monetaryItemTypemonetaryAmount of benefits expected to be paid in the next fiscal year following the latest fiscal year from a defined benefit plan.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 false220133false 4us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwous-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse2800000028USD$falsefalsefalsexbrli:monetaryItemTypemonetaryAmount of benefits expected to be paid in the second fiscal year following the latest fiscal year from a defined benefit plan.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 false220144false 4us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThreeus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse2700000027USD$falsefalsefalsexbrli:monetaryItemTypemonetaryAmount of benefits expected to be paid in the third fiscal year following the latest fiscal year from a defined benefit plan.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 false220155false 4us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFourus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse2700000027USD$falsefalsefalsexbrli:monetaryItemTypemonetaryAmount of benefits expected to be paid in the fourth fiscal year following the latest fiscal year from a defined benefit plan.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 false220166false 4us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFiveus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse2700000027USD$falsefalsefalsexbrli:monetaryItemTypemonetaryAmount of benefits expected to be paid in the fifth fiscal year following the latest fiscal year from a defined benefit plan.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 false220177false 4us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafterus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse131000000131USD$falsefalsefalsexbrli:monetaryItemTypemonetaryAmount of benefits expected to be paid in the five fiscal years after the fifth fiscal year following the latest fiscal year from a defined benefit plan.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 false22018- 20228false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2false USDtruefalse$eol_PE864322--13S-4-0005_STD_0_20121231_0_578345x638841http://www.sec.gov/CIK0001530804instant2012-12-31T00:00:000001-01-01T00:00:00falsefalseRetirement Plans [Member]us-gaap_MultiemployerPlanTypeAxisxbrldihttp://xbrl.org/2006/xbrlditrox_RetirementPlanMemberus-gaap_MultiemployerPlanTypeAxisexplicitMemberiso4217_USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$nanafalse0Retirement Plans [Member]9true 3us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]10false 4us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonthsus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse3200000032USD$falsefalsefalsexbrli:monetaryItemTypemonetaryAmount of benefits expected to be paid in the next fiscal year following the latest fiscal year from a defined benefit plan.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 false2201311false 4us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwous-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse3100000031USD$falsefalsefalsexbrli:monetaryItemTypemonetaryAmount of benefits expected to be paid in the second fiscal year following the latest fiscal year from a defined benefit plan.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 false2201412false 4us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThreeus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse3100000031USD$falsefalsefalsexbrli:monetaryItemTypemonetaryAmount of benefits expected to be paid in the third fiscal year following the latest fiscal year from a defined benefit plan.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 false2201513false 4us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFourus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse3000000030USD$falsefalsefalsexbrli:monetaryItemTypemonetaryAmount of benefits expected to be paid in the fourth fiscal year following the latest fiscal year from a defined benefit plan.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 false2201614false 4us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFiveus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse3100000031USD$falsefalsefalsexbrli:monetaryItemTypemonetaryAmount of benefits expected to be paid in the fifth fiscal year following the latest fiscal year from a defined benefit plan.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 false2201715false 4us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafterus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse153000000153USD$falsefalsefalsexbrli:monetaryItemTypemonetaryAmount of benefits expected to be paid in the five fiscal years after the fifth fiscal year following the latest fiscal year from a defined benefit plan.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 false22018- 202216false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse3false USDtruefalse$eol_PE864322--13S-4-0005_STD_0_20121231_0_578345x673672http://www.sec.gov/CIK0001530804instant2012-12-31T00:00:000001-01-01T00:00:00falsefalsePostretirement healthcare plan [Member]us-gaap_MultiemployerPlanTypeAxisxbrldihttp://xbrl.org/2006/xbrlditrox_PostretirementHealthcarePlansMemberus-gaap_MultiemployerPlanTypeAxisexplicitMemberiso4217_USDStandardhttp://www.xbrl.org/2003/iso4217USDiso42170USDUSD$nanafalse0Postretirement healthcare plan [Member]17true 3us-gaap_DefinedBenefitPlansAndOtherPostretirementBenefitPlansTableTextBlockLineItemsus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]18false 4us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonthsus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse10000001USD$falsefalsefalsexbrli:monetaryItemTypemonetaryAmount of benefits expected to be paid in the next fiscal year following the latest fiscal year from a defined benefit plan.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 false2201319false 4us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwous-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse10000001USD$falsefalsefalsexbrli:monetaryItemTypemonetaryAmount of benefits expected to be paid in the second fiscal year following the latest fiscal year from a defined benefit plan.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 false2201420false 4us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThreeus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse10000001USD$falsefalsefalsexbrli:monetaryItemTypemonetaryAmount of benefits expected to be paid in the third fiscal year following the latest fiscal year from a defined benefit plan.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 false2201521false 4us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFourus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse10000001USD$falsefalsefalsexbrli:monetaryItemTypemonetaryAmount of benefits expected to be paid in the fourth fiscal year following the latest fiscal year from a defined benefit plan.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 false2201622false 4us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFiveus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse10000001USD$falsefalsefalsexbrli:monetaryItemTypemonetaryAmount of benefits expected to be paid in the fifth fiscal year following the latest fiscal year from a defined benefit plan.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 false2201723false 4us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafterus-gaap_truecreditinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse60000006USD$falsetruefalsexbrli:monetaryItemTypemonetaryAmount of benefits expected to be paid in the five fiscal years after the fifth fiscal year following the latest fiscal year from a defined benefit plan.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920 false22018- 2022falsePension and Other Postretirement Healthcare Benefits - Summary of Expected Benefit Payments (Detail) (USD $)MillionsUnKnownUnKnownUnKnowntruefalsefalseSheethttp://imetrix.edgar-online.com/taxonomy/role/DisclosurePensionAndOtherPostretirementHealthcareBenefitsSummaryOfExpectedBenefitPayments123