Condensed Consolidated Statements of Changes in Equity (Unaudited) (Parenthetical)	6 Months Ended
Jun. 30, 2013	Jun. 30, 2012
Condensed Consolidated Statements of Changes in Equity (Unaudited) (Parenthetical) [Abstract]
Surrender of common stock to facilitate vesting of restricted stock, (in shares)		859
Reversal of compensation expense relating to forfeited restricted common stock and stock options (in shares)	3,000	500

Number of shares issued during the period as a result of stock bought back by the entity to facilitate vesting of restricted stock.

No definition available.

Name:	cbc_SurrenderOfCommonStockToFacilitateVestingOfRestrictedStockShares
Namespace Prefix:	cbc_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration