Securities In An Unrealized Loss Position Securities in an Unrealized Loss Position (Securities in an Unrealized Loss Position) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	$ 1,190,273	$ 3,085,977
Gross Unrealized Losses, Less than 12 Months	21,257	84,259
Fair Value, 12 Months or Greater	1,014,108	355,098
Gross Unrealized Losses, 12 Months or Greater	44,903	33,194
Fair Value, Total	2,204,381	3,441,075
Gross Unrealized Losses, Total	66,160	117,453
U.S. government and government agency
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	191,360	260,882
Gross Unrealized Losses, Less than 12 Months	4,176	7,927
Fair Value, 12 Months or Greater	74,427	2,163
Gross Unrealized Losses, 12 Months or Greater	3,377	55
Fair Value, Total	265,787	263,045
Gross Unrealized Losses, Total	7,553	7,982
State and municipal
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	136,081	899,613
Gross Unrealized Losses, Less than 12 Months	1,796	24,503
Fair Value, 12 Months or Greater	185,605	87,345
Gross Unrealized Losses, 12 Months or Greater	3,767	5,334
Fair Value, Total	321,686	986,958
Gross Unrealized Losses, Total	5,563	29,837
Mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	129,004	578,603
Gross Unrealized Losses, Less than 12 Months	725	17,964
Fair Value, 12 Months or Greater	341,219	140,648
Gross Unrealized Losses, 12 Months or Greater	13,087	8,965
Fair Value, Total	470,223	719,251
Gross Unrealized Losses, Total	13,812	26,929
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	549,991	1,013,373
Gross Unrealized Losses, Less than 12 Months	7,099	17,066
Fair Value, 12 Months or Greater	285,261	105,074
Gross Unrealized Losses, 12 Months or Greater	11,393	13,034
Fair Value, Total	835,252	1,118,447
Gross Unrealized Losses, Total	18,492	30,100
Foreign government
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	183,837	320,215
Gross Unrealized Losses, Less than 12 Months	7,461	16,286
Fair Value, 12 Months or Greater	101,882	0
Gross Unrealized Losses, 12 Months or Greater	10,274	0
Fair Value, Total	285,719	320,215
Gross Unrealized Losses, Total	17,735	16,286
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	1,190,273	3,072,686
Gross Unrealized Losses, Less than 12 Months	21,257	83,746
Fair Value, 12 Months or Greater	988,394	335,230
Gross Unrealized Losses, 12 Months or Greater	41,898	27,388
Fair Value, Total	2,178,667	3,407,916
Gross Unrealized Losses, Total	63,155	111,134
Common stocks
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	0	0
Gross Unrealized Losses, Less than 12 Months	0	0
Fair Value, 12 Months or Greater	0	0
Gross Unrealized Losses, 12 Months or Greater	0	0
Fair Value, Total	0	0
Gross Unrealized Losses, Total	0	0
Preferred stocks
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	0	13,291
Gross Unrealized Losses, Less than 12 Months	0	513
Fair Value, 12 Months or Greater	25,714	19,868
Gross Unrealized Losses, 12 Months or Greater	3,005	5,806
Fair Value, Total	25,714	33,159
Gross Unrealized Losses, Total	3,005	6,319
Equity securities available for sale
Schedule of Available-for-sale Securities [Line Items]
Fair Value, Less than 12 Months	0	13,291
Gross Unrealized Losses, Less than 12 Months	0	513
Fair Value, 12 Months or Greater	25,714	19,868
Gross Unrealized Losses, 12 Months or Greater	3,005	5,806
Fair Value, Total	25,714	33,159
Gross Unrealized Losses, Total	$ 3,005	$ 6,319