Other Comprehensive Income (Loss) (Reclassifications From Accumulated Other Comprehensive Income Into Income, By Component) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Reclassification Out Of Accumulated Other Comprehensive Income [Line Items]
Other-than-temporary impairment losses recognized in net income	$ (3,675)	$ 0	$ (12,080)	$ (5,092)
Net realized investment gains, excluding other-than-temporary impairment losses	20,916	6,105	50,500	16,768
Income Before Income Taxes	115,891	100,286	330,227	339,807
Underwriting, acquisition and insurance expenses	(375,580)	(379,652)	(740,268)	(720,337)
Income taxes	(35,218)	(7,833)	(85,908)	(53,348)
Net Income	80,673	92,453	244,319	286,459
Reclassification Out Of Accumulated Other Comprehensive Income [Member] | Unrealized Holding Gains On Available-For-Sale Securities [Member]
Reclassification Out Of Accumulated Other Comprehensive Income [Line Items]
Other-than-temporary impairment losses recognized in net income	(3,675)	0	(12,080)	(5,092)
Net realized investment gains, excluding other-than-temporary impairment losses	16,575	7,560	43,440	24,801
Income Before Income Taxes	12,900	7,560	31,360	19,709
Income taxes	(2,333)	(2,576)	(7,810)	(5,672)
Net Income	10,567	4,984	23,550	14,037
Reclassification Out Of Accumulated Other Comprehensive Income [Member] | Net Actuarial Pension Loss [Member]
Reclassification Out Of Accumulated Other Comprehensive Income [Line Items]
Underwriting, acquisition and insurance expenses	(480)	(586)	(1,045)	(1,165)
Income taxes	86	117	188	233
Net Income	$ (394)	$ (469)	$ (857)	$ (932)