Schedule II Condensed Financial Information of Registrant (Details 2) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash flows - operating activities
Interest expense paid	$ (13,902)us-gaap_InterestPaid	$ (13,825)us-gaap_InterestPaid	$ (13,948)us-gaap_InterestPaid
Federal income taxes recovered (paid)	(29,195)us-gaap_IncomeTaxesPaidNet	(33,672)us-gaap_IncomeTaxesPaidNet	(14,444)us-gaap_IncomeTaxesPaidNet
Other, net, including settlement of payables to subsidiaries	(15,437)	(16,135)	(18,124)
Net cash provided by operating activities	221,933	205,936	202,848
Cash flows - investing activities
Net cash provided by (used in) investing activities	(565,515)	(598,326)	(354,798)
Cash flows - financing activities
Dividends paid to shareholders	(39,237)us-gaap_PaymentsOfDividendsCommonStock	(32,550)us-gaap_PaymentsOfDividendsCommonStock	(22,541)us-gaap_PaymentsOfDividendsCommonStock
Exercise of stock options	8,252	19,336	5,421
Net cash used in financing activities	337,068	395,398	159,679
Net increase (decrease) in cash	(6,514)us-gaap_CashPeriodIncreaseDecrease	3,008us-gaap_CashPeriodIncreaseDecrease	7,729us-gaap_CashPeriodIncreaseDecrease
Cash at beginning of period	18,189us-gaap_Cash	15,181us-gaap_Cash	7,452us-gaap_Cash
Cash at end of period	11,675us-gaap_Cash	18,189us-gaap_Cash	15,181us-gaap_Cash
Parent Company [Member]
Cash flows - operating activities
Interest expense paid	(13,902)	(13,825)	(13,948)
Federal income taxes recovered (paid)	8,740	5,996	(118)
Cash dividends received from subsidiaries	46,000	41,000	50,000
Other, net, including settlement of payables to subsidiaries	(188)	(21,235)	7,703
Net cash provided by operating activities	40,650	11,936	43,637
Cash flows - investing activities
Net (increase) decrease in investments	(4,647)	5,488	(10,762)
Net cash provided by (used in) investing activities	(4,647)	5,488	(10,762)
Cash flows - financing activities
Dividends paid to shareholders	(39,237)	(32,550)	(22,541)
Acquisition of treasury stock	(5,411)	(3,889)	(15,735)
Exercise of stock options	8,252	19,336	5,421
Net cash used in financing activities	(36,396)	(17,103)	(32,855)
Net increase (decrease) in cash	(393)	321	20
Cash at beginning of period	470	149	129
Cash at end of period	$ 77	$ 470	$ 149

Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Excludes cash and cash equivalents within disposal group and discontinued operation.

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The amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income, net of any cash received during the current period as refunds for the overpayment of taxes.

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Amount of cash inflow (outflow) from investing activities, including discontinued operations. Investing activity cash flows include making and collecting loans and acquiring and disposing of debt or equity instruments and property, plant, and equipment and other productive assets.

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Amount of cash inflow (outflow) from operating activities, including discontinued operations. Operating activity cash flows include transactions, adjustments, and changes in value not defined as investing or financing activities.

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Cash payments made during the current period for operating activities other than those that have been specifically listed above.

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