Label	Element	Value
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	$ 4,600,000
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	5,500,000
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	5,300,000
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	6,700,000
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	6,000,000.0
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	5,000,000.0
Partners' Capital Account, Unit-based Payment Arrangement, Amount	us-gaap_PartnersCapitalAccountUnitBasedCompensation	100,000
Partners' Capital Account, Unit-based Payment Arrangement, Amount	us-gaap_PartnersCapitalAccountUnitBasedCompensation	100,000
Partners' Capital Account, Unit-based Payment Arrangement, Amount	us-gaap_PartnersCapitalAccountUnitBasedCompensation	100,000
Partners' Capital Account, Unit-based Payment Arrangement, Amount	us-gaap_PartnersCapitalAccountUnitBasedCompensation	100,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	33,000,000.0
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	37,600,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	31,600,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	37,600,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	37,600,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	34,300,000
General Partner [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	200,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	1,200,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	400,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	1,200,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	700,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	1,200,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	1,200,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	1,200,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	200,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	1,200,000
Member Units [Member] | General Public [Member] | Common Units [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	16,900,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	18,000,000.0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	16,900,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	20,500,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	20,100,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	18,500,000
Partners' Capital Account, Unit-based Payment Arrangement, Amount	us-gaap_PartnersCapitalAccountUnitBasedCompensation	100,000
Partners' Capital Account, Unit-based Payment Arrangement, Amount	us-gaap_PartnersCapitalAccountUnitBasedCompensation	100,000
Partners' Capital Account, Unit-based Payment Arrangement, Amount	us-gaap_PartnersCapitalAccountUnitBasedCompensation	100,000
Partners' Capital Account, Unit-based Payment Arrangement, Amount	us-gaap_PartnersCapitalAccountUnitBasedCompensation	100,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	14,400,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	16,600,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	15,500,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	16,600,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	16,600,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	15,000,000.0
Member Units [Member] | BP Holdco [Member] | Subordinated Units [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	22,500,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	18,500,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	18,400,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	22,100,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	19,700,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	20,200,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	18,200,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	16,400,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	16,900,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	15,800,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	18,200,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	18,200,000
Member Units [Member] | BP Holdco [Member] | Common Units [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	2,000,000.0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	1,600,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	1,900,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	1,700,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	1,600,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	1,800,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	1,600,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	1,400,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	1,500,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	1,400,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	1,600,000
Partners' Capital Account, Distributions	us-gaap_PartnersCapitalAccountDistributions	1,600,000
Noncontrolling Interest [Member]
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	5,800,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	4,700,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	3,500,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	4,800,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	4,800,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	4,400,000
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	5,500,000
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	4,600,000
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	5,300,000
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	5,000,000.0
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	6,000,000.0
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	$ 6,700,000