Common and Preferred Stock, Stock-Based Plan Descriptions and Share Information (Details)	12 Months Ended
Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of stock-based plans	2

Number of stock-based compensation plans available to qualifying employees.

No definition available.

Name:	cnl_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfStockBasedPlans
Namespace Prefix:	cnl_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration