CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) (USD $) In Thousands, unless otherwise specified	9 Months Ended
Sep. 30, 2012
CONSOLIDATED STATEMENTS OF CASH FLOWS
Public offering of common units, underwriting discounts and commissions	$ 7,590

The cash outflow for cost incurred directly with the public offering of common units.

No definition available.

Name:	cpno_PaymentsPublicOfferingStockIssuanceCosts
Namespace Prefix:	cpno_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration