Investments (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012 securities	Dec. 31, 2011 securities
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities in unrealized loss position, number of positions	57	76
Available-for-sale securities, Estimated Fair Value	$ 243,286	$ 587,887
Gross unrealized losses	11,449	17,670
Number of available-for-sale securities positions in a continuous unrealized loss position for greater than one year at period end	12	17
Available-for-sale securities, Estimated Fair Value, 12 months or longer	22,196	45,786
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	842	2,355
Fixed maturities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Estimated Fair Value	163,920	176,302
Gross unrealized losses	10,841	13,520
Number of available-for-sale securities positions in a continuous unrealized loss position for greater than one year at period end	11	16
Available-for-sale securities, Estimated Fair Value, 12 months or longer	22,097	27,261
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	831	2,349
Equity securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Estimated Fair Value	32,371	115,594
Gross unrealized losses	601	4,146
Number of available-for-sale securities positions in a continuous unrealized loss position for greater than one year at period end	1	1
Available-for-sale securities, Estimated Fair Value, 12 months or longer	99	18,525
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	$ 11	$ 6