Investments (Narrative) (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013 security	Jun. 30, 2012	Jun. 30, 2013 security	Jun. 30, 2012	Dec. 31, 2012 security
Investments [Abstract]
Gross gains on investments	$ 1,600,000	$ 1,400,000	$ 2,800,000	$ 1,500,000
Gross losses on investments	43,000	200,000	52,000	400,000
Proceeds from sale of investment securities	$ 9,900,000	$ 6,000,000	$ 17,700,000	$ 6,200,000
Number of debt security positions	64		64		56