Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2016

Stockholders' Equity Note [Abstract]

Schedule of Stock by Class [Table Text Block]

Reconciliation of Outstanding Common Stock
	Class A					Class B			Total
	Shares		Dollars			Shares	Dollars		Shares		Dollars
	(Dollars in thousands)
Outstanding at January 1, 2014	24,742,942		$	134,993		11,413	$	72	24,754,355		$	135,065
Issuance of common stock under compensation plans	390,707		12,028			—	—		390,707		12,028
Purchase of common stock	(429,746	)	(2,396		)	—	—		(429,746	)	(2,396		)
Outstanding at December 31, 2014	24,703,903		144,625			11,413	72		24,715,316		144,697
Issuance of common stock under compensation plans	159,764		5,022			—	—		159,764		5,022
Purchase of common stock	(66,904	)	(399		)	—	—		(66,904	)	(399		)
Outstanding at December 31, 2015	24,796,763		149,248			11,413	72		24,808,176		149,320
Issuance of common stock under compensation plans	96,101		3,718			—	—		96,101		3,718
Purchase of common stock	(10,322	)	(63		)	—	—		(10,322	)	(63		)
Outstanding at December 31, 2016	24,882,542		$	152,903		11,413	$	72	24,893,955		$	152,975

Comprehensive Income (Loss) [Table Text Block]

Accumulated Other Comprehensive Income, Net of Tax and Other Offsets
	Unrealized Net Investment Gains (Losses) (1)			Accumulated Non-Credit Impairment Gains (Losses)			Underfunded Portion of Certain Benefit Plans (2)			Total
	(Dollars in thousands)
Balance at January 1, 2014	$	126,587		$	(1,366	)	$	(6,154	)	$	119,067
Other comprehensive income before reclassifications	141,947			2,497			—			144,444
Reclassification adjustments	(2,323		)	—			(2,778		)	(5,101		)
Balance at December 31, 2014	266,211			1,131			(8,932		)	258,410
Other comprehensive income before reclassifications	(143,731		)	(1,155		)	—			(144,886		)
Reclassification adjustments	(1,693		)	(90		)	2,791			1,008
Balance at December 31, 2015	120,787			(114		)	(6,141		)	114,532
Other comprehensive income before reclassifications	37,895			1,901			—			39,796
Reclassification adjustments	(1,719		)	(1,476		)	(1,578		)	(4,773		)
Balance at December 31, 2016	$	156,963		$	311		$	(7,719	)	$	149,555

Reclassification out of Accumulated Other Comprehensive Income [Table Text Block]

Accumulated Other Comprehensive Income Reclassification Adjustments
	Year ended December 31, 2016
	Unrealized Net Investment Gains (Losses) (1)			Accumulated Non-Credit Impairment Losses (1)			Underfunded Portion of Certain Benefit Plans (2)			Total
	(Dollars in thousands)
Realized capital gains on sales of investments	$	(1,799	)	$	—		$	—		$	(1,799	)
Adjustments for assumed changes in deferred policy acquisition costs, value of insurance in force acquired, unearned revenue reserve and policyholder liabilities	(845		)	180			—			(665		)
Other than temporary impairment losses	—			(2,451		)	—			(2,451		)
Other expenses - change in unrecognized postretirement items:
Prior service costs	—			—			(1		)	(1		)
Net actuarial gain	—			—			(2,425		)	(2,425		)
Reclassifications before income taxes	(2,644		)	(2,271		)	(2,426		)	(7,341		)
Income taxes	925			795			848			2,568
Reclassification adjustments	$	(1,719	)	$	(1,476	)	$	(1,578	)	$	(4,773	)

	Year ended December 31, 2015
	Unrealized Net Investment Gains (Losses) (1)			Accumulated Non-Credit Impairment Losses (1)			Underfunded Portion of Certain Benefit Plans (2)			Total
	(Dollars in thousands)
Realized capital gains on sales of investments	$	(2,829	)	$	—		$	—		$	(2,829	)
Adjustments for assumed changes in deferred policy acquisition costs, value of insurance in force acquired, unearned revenue reserve and policyholder liabilities	224			7			—			231
Other than temporary impairment losses	—			(146		)	—			(146		)
Other expenses - change in unrecognized postretirement items:
Prior service costs	—			—			(12		)	(12		)
Net actuarial loss	—			—			4,306			4,306
Reclassifications before income taxes	(2,605		)	(139		)	4,294			1,550
Income taxes	912			49			(1,503		)	(542		)
Reclassification adjustments	$	(1,693	)	$	(90	)	$	2,791		$	1,008

	Year ended December 31, 2014
	Unrealized Net Investment Gains (Losses) (1)			Accumulated Non-Credit Impairment Losses (1)		Underfunded Portion of Certain Benefit Plans (2)			Total
	(Dollars in thousands)
Realized capital gains on sales of investments	$	(3,760	)	$	—	$	—		$	(3,760	)
Adjustments for assumed changes in deferred policy acquisition costs, value of insurance in force acquired, unearned revenue reserve and policyholder liabilities	186			—		—			186
Other expenses - change in unrecognized postretirement items:
Prior service costs	—			—		(11		)	(11		)
Net actuarial gain	—			—		(4,263		)	(4,263		)
Reclassifications before income taxes	(3,574		)	—		(4,274		)	(7,848		)
Income taxes	1,251			—		1,496			2,747
Reclassification adjustments	$	(2,323	)	$	—	$	(2,778	)	$	(5,101	)

(1) See Note 2 for further information.

(2) For descriptions of the underfunded portion of our postretirement benefit plans, see Note 8 - Other Retirement Plans, and for certain other defined benefit plans, see Note 8 - Defined Benefit Plans.