Investment Securities: (Details) (USD $) In Thousands | 9 Months Ended | 12 Months Ended | |||
|---|---|---|---|---|---|
Sep. 30, 2011 | Dec. 31, 2010 | ||||
| Schedule of Available-for-sale Securities [Line Items] | |||||
| Available-for-sale Securities, Gross Unrealized Gains | $ 0 | $ 0 | |||
| Available-for-sale Securities, Gross Realized Gain (Loss) | 0 | 0 | |||
| Debt Securities Maturity Date Range Low | 2011 | ||||
| Debt Securities Maturity Date Range High | 2037 | ||||
| Debt Securities Callable Period | 1Y | ||||
| Investment securities | 52,153 | 14,507 | [1] | ||
Federal tax-exempt debt securities [Member] | |||||
| Schedule of Available-for-sale Securities [Line Items] | |||||
| Investment securities | 31,051 | 11,687 | |||
Corporate Bond Securities [Member] | |||||
| Schedule of Available-for-sale Securities [Line Items] | |||||
| Investment securities | 16,023 | ||||
| Available-for-sale Securities | 0 | ||||
Certificates of deposit [Member] | |||||
| Schedule of Available-for-sale Securities [Line Items] | |||||
| Investment securities | $ 5,079 | $ 2,820 | |||
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