Accounting Policies and Other Matters (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2012
Accounting Policies [Abstract]
Maximum period of fair value refinement after transaction closing date	1 year
Adjustments to acquisition gains	$ 0

Gain on Purchase of Business, Adjustments Related to Acquisition Date Fair Values

No definition available.

Name:	fcnca_GainOnPurchaseOfBusinessAdjustmentsRelatedToAcquisitionDateFairValues
Namespace Prefix:	fcnca_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration