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Statements of Cash Flow (Cash Flow Supplemental Disclosures) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Interest	$ 21,892	$ 22,221	$ 21,465
Federal income tax	39,500	22,699	20,000
Stock split related to equity securities, AFS	4,239	334	0
Assets acquired under capital lease arrangements	6,760	5,642	2,583
Non-cash purchase of property and equipment	0	338	20
AFS Fixed Income Securities [Member]
Tax- free exchange of fixed income securities	36,792	20,781	37,965
Held-to-maturity Securities [Member]
Tax- free exchange of fixed income securities	15,257	4,289	$ 15,820
National Flood Insurance Program [Member]
Restricted cash	$ 11,900	$ 6,000

X

- Definition

The increase during the period in capital lease obligations due to entering into new capital leases.

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