Disclosures About Fair Value of Financial Instruments (Details 2) (Level 3 [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2012
Statement of changes in Level 3 assets measured at fair value on a recurring basis
Balance at beginning	$ 22,336	$ 22,111
Total losses included in other comprehensive income (before taxes)	(343)	(14)
Amortization included in interest income	(158)	(262)
Purchases	5,000	5,000
Balance at ending	26,835	26,835
Mortgage-backed Securities [Member]
Statement of changes in Level 3 assets measured at fair value on a recurring basis
Balance at beginning	2,790	2,894
Total losses included in other comprehensive income (before taxes)	0	0
Amortization included in interest income	(158)	(262)
Purchases	0	0
Balance at ending	2,632	2,632
Corporate Notes [Member]
Statement of changes in Level 3 assets measured at fair value on a recurring basis
Balance at beginning	19,546	19,217
Total losses included in other comprehensive income (before taxes)	(343)	(14)
Amortization included in interest income	0	0
Purchases	5,000	5,000
Balance at ending	$ 24,203	$ 24,203