Debt (Tables)

9 Months Ended

Sep. 30, 2016

Debt Disclosure [Abstract]

Schedule of Long-term Debt Instruments [Table Text Block]

The amortized cost of debt outstanding at September 30, 2016 and December 31, 2015 was:

(Dollars in Millions)	Sep 30, 2016		Dec 31, 2015
Senior Notes:
6.00% Senior Notes due May 15, 2017	$	359.6	$	359.1
4.35% Senior Notes due February 15, 2025	247.6		247.4
7.375% Subordinated Debentures due February 27, 2054	144.1		144.1
Total Debt Outstanding	$	751.3	$	750.6

Schedule of Interest Expense [Table Text Block]

Interest Expense, including facility fees, accretion of discount and amortization of issuance costs, for the nine and three months endedSeptember 30, 2016 and 2015 was:

	Nine Months Ended						Three Months Ended
(Dollars in Millions)	Sep 30, 2016			Sep 30, 2015			Sep 30, 2016			Sep 30, 2015
Notes Payable under Revolving Credit Agreement	$	0.6		$	0.6		$	0.2		$	0.2
Federal Home Loan Bank of Dallas	—			—			—			—
Federal Home Loan Bank of Chicago	—			—			—			—
Senior Notes Payable:
6.00% Senior Notes due November 30, 2015	—			3.7			—			—
6.00% Senior Notes due May 15, 2017	16.7			16.7			5.6			5.6
4.35% Senior Notes due February 15, 2025	8.3			6.7			2.7			2.8
7.375% Subordinated Debentures due February 27, 2054	8.3			8.3			2.8			2.8
Interest Expense before Capitalization of Interest	33.9			36.0			11.3			11.4
Capitalization of Interest	(0.5		)	(0.6		)	(0.2		)	(0.1		)
Total Interest Expense	$	33.4		$	35.4		$	11.1		$	11.3

Schedule of Interest Paid [Table Text Block]

Interest paid, including facility fees, for the nine and three months endedSeptember 30, 2016 and 2015 was:

	Nine Months Ended				Three Months Ended
(Dollars in Millions)	Sep 30, 2016		Sep 30, 2015		Sep 30, 2016		Sep 30, 2015
Notes Payable under Revolving Credit Agreement	$	0.5	$	1.3	$	0.2	$	0.2
Federal Home Loan Bank of Dallas	—		—		—		—
Federal Home Loan Bank of Chicago	—		—		—		—
Senior Notes Payable:
6.00% Senior Notes due November 30, 2015	—		4.8		—		—
6.00% Senior Notes due May 15, 2017	10.8		10.8		—		—
4.35% Senior Notes due February 15, 2025	10.9		5.2		5.5		5.2
7.375% Subordinated Debentures due February 27, 2054	8.3		8.3		2.8		2.8
Total Interest Paid	$	30.5	$	30.4	$	8.5	$	8.2