Investments Investments (Details 4) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2015	Mar. 31, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Investments, Debt and Equity Securities [Abstract]
Taxable interest	$ 7,577	$ 7,473	$ 7,668	$ 15,050	$ 14,584
Non-taxable interest	4,808	3,894	3,333	8,702	6,661
Dividend income	2,185	828	985	3,013	1,564
Total interest income on investment securities	$ 14,570	$ 12,195	$ 11,986	$ 26,765	$ 22,809