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Adoption of Accounting Pronouncements Adoption of Accounting Pronoucements (Tables) | 9 Months Ended
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Sep. 30, 2012
Adoption of Accounting Pronouncements [Abstract] |
Schedule Of New Accounting Pronouncements Balance Sheet Information [Table Text Block] |
Balance Sheet Information December 31, 2011 |  |  |  |  |  |
($ in thousands) |  | As Originally Reported |  | Effect of Change |  | As Adopted
Deferred policy acquisition costs |  | $ | 214,069 |  |  | (78,308 | ) |  | 135,761 |
Deferred federal income tax recoverable 1 |  | 92,078 |  |  | 27,408 |  |  | 119,486 |
Retained earnings |  | 1,167,219 |  |  | (50,900 | ) |  | 1,116,319 |
1 Included in the deferred federal income tax recoverable amount is an adjustment of $0.6 million reflecting the revaluation of a deferred tax asset acquired as part of the purchase of Mesa Underwriters Specialty Insurance Company ("MUSIC" ). For additional information, see Footnote 14, "Federal Income Taxes" below.
Schedule Of New Accounting Pronouncements Income Statement Information [Table Text Block] | 1
Income Statement Information Quarter ended September 30, 2011 |  |  |  |  |  |
($ in thousands, except per share amounts) |  | As Originally Reported |  | Effect of Change |  | As Adopted
Policy acquisition costs |  | $ | 119,456 |  |  | (3,345 | ) |  | 116,111 |
Deferred federal income tax expense (benefit) |  | (1,335 | ) |  | 1,171 |  |  | (164 | )
Net income (loss) |  | (20,142 | ) |  | 2,174 |  |  | (17,968 | )
Net income (loss) per share: |  |  |  |  |  |  |  |  |
Basic |  | $ | (0.37 | ) |  | 0.04 |  |  | (0.33 | )
Diluted |  | (0.37 | ) |  | 0.04 |  |  | (0.33 | )
Income Statement Information Nine months ended September 30, 2011 |  |  |  |  |  |
($ in thousands, except per share amounts) |  | As Originally Reported |  | Effect of Change |  | As Adopted
Policy acquisition costs |  | $ | 346,729 |  |  | (411 | ) |  | 346,318 |
Deferred federal income tax expense (benefit) |  | (3,603 | ) |  | 144 |  |  | (3,459 | )
Net income (loss) |  | $ | 3,732 |  |  | 267 |  |  | 3,999 |
Net income (loss) per share: |  |  |  |  |  |
Basic |  | $ | 0.07 |  |  | — |  |  | 0.07 |
Diluted |  | 0.07 |  |  | — |  |  | 0.07 |
Schedule Of New Accounting Pronouncements Cash Flow Statement Information [Table Text Block] |
Cash Flow Information Nine months ended September 30, 2011 |  |  |  |  |  |
($ in thousands, except per share amounts) |  | As Originally Reported |  | Effect of Change |  | As Adopted
(Increase) decrease in deferred policy acquisition costs |  | $ | (10,417 | ) |  | (411 | ) |  | (10,828 | )
Increase (decrease) in net federal income taxes recoverable |  | (9,570 | ) |  | 144 |  |  | (9,426 | )

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