Summary of Investments (Investments in Unrealized Loss Position) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013 issues	Dec. 31, 2012 issues
Schedule of Investments [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Less than Twelve Months, Number of Issues	182	107
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	$ 289,920	$ 182,504
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	4,386	2,568
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Number of Issues	35	66
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	17,490	37,565
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	891	2,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	307,410	220,069
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	5,277	4,568
Debt Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Less than Twelve Months, Number of Issues	167	91
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	288,761	181,198
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	4,240	2,386
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Number of Issues	12	34
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	14,483	32,783
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	594	1,482
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	303,244	213,981
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	4,834	3,868
U.S. Treasury [Member]
Schedule of Investments [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Less than Twelve Months, Number of Issues	2	2
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	1,717	1,724
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	4	5
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Number of Issues	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,717	1,724
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	4	5
U.S. Government Agency [Member]
Schedule of Investments [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Less than Twelve Months, Number of Issues	14	5
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	45,452	17,654
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	243	67
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Number of Issues	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	45,452	17,654
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	243	67
States, Municipalities and Political Subdivisions [Member]
Schedule of Investments [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Less than Twelve Months, Number of Issues	82	31
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	83,557	41,775
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	1,662	819
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Number of Issues	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	83,557	41,775
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	1,662	819
Foreign Bonds [Member]
Schedule of Investments [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Less than Twelve Months, Number of Issues	1	1
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	3,327	3,323
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	31	48
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Number of Issues	0	1
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	558
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0	14
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	3,327	3,881
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	31	62
Public Utilities [Member]
Schedule of Investments [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Less than Twelve Months, Number of Issues	2	2
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	3,277	3,155
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	7	32
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Number of Issues	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	3,277	3,155
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	7	32
Corporate Bonds [Member] | Industrial [Member]
Schedule of Investments [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Less than Twelve Months, Number of Issues	2	4
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	6,069	12,194
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	101	109
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Number of Issues	0	1
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	2,897
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0	103
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	6,069	15,091
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	101	212
Corporate Bonds [Member] | Consumer Goods and Service [Member]
Schedule of Investments [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Less than Twelve Months, Number of Issues	1	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	2,344	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	11	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Number of Issues	6	7
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	3,301	4,606
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	88	151
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	5,645	4,606
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	99	151
Corporate Bonds [Member] | Health Care [Member]
Schedule of Investments [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Less than Twelve Months, Number of Issues	3	3
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	7,336	7,416
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	133	80
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Number of Issues	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	7,336	7,416
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	133	80
Corporate Bonds [Member] | Technology, Media and Telecommunications [Member]
Schedule of Investments [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Less than Twelve Months, Number of Issues	5	5
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	18,271	13,402
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	701	198
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Number of Issues	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	18,271	13,402
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	701	198
Corporate Bonds [Member] | Financial Services [Member]
Schedule of Investments [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Less than Twelve Months, Number of Issues	2	2
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	3,883	1,005
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	4	1
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Number of Issues	3	24
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	11,139	24,693
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	373	1,058
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	15,022	25,698
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	377	1,059
Mortgage Backed Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Less than Twelve Months, Number of Issues	7	7
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	4,244	4,472
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	25	21
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Number of Issues	2	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	22	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	1	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	4,266	4,472
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	26	21
Collateralized Mortgage Obligations [Member]
Schedule of Investments [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Less than Twelve Months, Number of Issues	46	27
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	109,284	74,702
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	1,318	1,004
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Number of Issues	1	1
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	21	29
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	132	156
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	109,305	74,731
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	1,450	1,160
Equity Securities [Member]
Schedule of Investments [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Less than Twelve Months, Number of Issues	15	16
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	1,159	1,306
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	146	182
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Number of Issues	23	32
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	3,007	4,782
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	297	518
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	4,166	6,088
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	443	700
Redeemable Preferred Stocks [Member]
Schedule of Investments [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Less than Twelve Months, Number of Issues		2
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value		376
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses		2
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Number of Issues		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		376
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses		2
Common Stocks [Member] | Public Utilities [Member]
Schedule of Investments [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Less than Twelve Months, Number of Issues	3	3
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	259	225
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	49	83
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Number of Issues	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	259	225
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	49	83
Common Stocks [Member] | Industrial [Member]
Schedule of Investments [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Less than Twelve Months, Number of Issues	1	4
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	278	482
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	36	52
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Number of Issues	7	9
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	529	621
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	88	122
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	807	1,103
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	124	174
Common Stocks [Member] | Consumer Goods and Service [Member]
Schedule of Investments [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Less than Twelve Months, Number of Issues	4	2
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	243	280
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	25	19
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Number of Issues	3	4
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	62	372
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	17	31
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	305	652
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	42	50
Common Stocks [Member] | Health Care [Member]
Schedule of Investments [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Less than Twelve Months, Number of Issues	1	1
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	33	31
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	1	2
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Number of Issues	1	3
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	470	896
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	24	123
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	503	927
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	25	125
Common Stocks [Member] | Technology, Media and Telecommunications [Member]
Schedule of Investments [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Less than Twelve Months, Number of Issues	5	5
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	299	241
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	16	7
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Number of Issues	5	7
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	197	581
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	64	88
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	496	822
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	80	95
Common Stocks [Member] | Financial Services [Member]
Schedule of Investments [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Less than Twelve Months, Number of Issues	1	1
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	47	47
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	19	19
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Number of Issues	5	7
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	538	1,109
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	84	126
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	585	1,156
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	103	145
Nonredeemable Preferred Stocks [Member]
Schedule of Investments [Line Items]
Available-for-sale, Securities in Unrealized Loss Positions, Less than Twelve Months, Number of Issues	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	0	0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Number of Issues	2	2
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	1,211	1,203
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	20	28
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	1,211	1,203
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	$ 20	$ 28