Basis of Presentation (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011	Dec. 31, 2010
Summary of financial statement amounts previously reported
Total shareholders' equity as previously reported.					$ 1,086,926	$ 880,007
Effect of change in accounting principle, net of taxes:
Retained earnings	869,729		869,729		840,644
Total shareholders' equity	1,143,538	899,553	1,143,538	899,553	1,055,353
Net income (loss)
As previously reported		(11,817)		14,124
Net income (loss)	13,103	(11,851)	39,774	13,956
Costs Associated with Acquiring or Renewing Insurance Contracts [Member]
Effect of change in accounting principle, net of taxes:
Retained earnings					(34,425)	(34,447)
Accumulated other comprehensive income (loss), net of taxes (Net unrealized gains and losses on fixed maturities and equity securities)					2,852	1,531
Total shareholders' equity					1,055,353	847,091
Net income (loss)
Effect of change in accounting principle, net of taxes		(34)		(168)
Net income (loss)		$ (11,851)		$ 13,956