Investment Securities (Details 4) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Fair value of investments
Total investment securities	$ 176,142	$ 134,262
Fair Value on Recurring Basis | Level 1
Fair value of investments
Total investment securities	132,822	67,859
Fair Value on Recurring Basis | Level 1 | Common Stock
Fair value of investments
Total investment securities	37	37
Fair Value on Recurring Basis | Level 1 | Affiliated mutual funds
Fair value of investments
Total investment securities	132,785	67,822
Fair Value on Recurring Basis | Level 2
Fair value of investments
Total investment securities	43,320	66,403
Fair Value on Recurring Basis | Level 2 | Mortgage-backed securities
Fair value of investments
Total investment securities	54	74
Fair Value on Recurring Basis | Level 2 | Municipal bonds
Fair value of investments
Total investment securities	501	3,036
Fair Value on Recurring Basis | Level 2 | Corporate bonds
Fair value of investments
Total investment securities	42,765	63,293
Fair Value on Recurring Basis | Total
Fair value of investments
Total investment securities	176,142	134,262
Fair Value on Recurring Basis | Total | Mortgage-backed securities
Fair value of investments
Total investment securities	54	74
Fair Value on Recurring Basis | Total | Municipal bonds
Fair value of investments
Total investment securities	501	3,036
Fair Value on Recurring Basis | Total | Corporate bonds
Fair value of investments
Total investment securities	42,765	63,293
Fair Value on Recurring Basis | Total | Common Stock
Fair value of investments
Total investment securities	37	37
Fair Value on Recurring Basis | Total | Affiliated mutual funds
Fair value of investments
Total investment securities	$ 132,785	$ 67,822