CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Parenthetical) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS)
Network operations, equity-based compensation expense	$ 507	$ 529	$ 510
Selling, general, and administrative, equity-based compensation expense	$ 8,212	$ 7,794	$ 7,185

This element represents the expenses related to equity based compensation, which includes selling, general and administrative expenses, during the reporting period by the entity.

No definition available.

Name:	ccoi_SellingGeneralAndAdministrativeExpensesIncludeEquityBasedCompensationExpense
Namespace Prefix:	ccoi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration