Debt (Tables)

3 Months Ended

Mar. 31, 2016

Debt Disclosure [Abstract]

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

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

(Dollars in Millions)	Mar 31, 2016		Dec 31, 2015
Senior Notes:
6.00% Senior Notes due May 15, 2017	$	359.3	$	359.1
4.35% Senior Notes due February 15, 2025	247.5		247.4
7.375% Subordinated Debentures due February 27, 2054	144.1		144.1
Total Debt Outstanding	$	750.9	$	750.6

Schedule of Interest Expense [Table Text Block]

Interest Expense, including facility fees, accretion of discount and amortization of issuance costs, for the three months endedMarch 31, 2016 and 2015 was:

	Three Months Ended
(Dollars in Millions)	Mar 31, 2016			Mar 31, 2015
Notes Payable under Revolving Credit Agreement	$	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	5.6			5.6
4.35% Senior Notes due February 15, 2025	2.8			1.1
7.375% Subordinated Debentures due February 27, 2054	2.8			2.8
Interest Expense before Capitalization of Interest	11.4			13.4
Capitalization of Interest	(0.2		)	(0.2		)
Total Interest Expense	$	11.2		$	13.2

Schedule of Interest Paid [Table Text Block]

Interest paid, including facility fees, for the three months endedMarch 31, 2016 and 2015 was:

	Three Months Ended
(Dollars in Millions)	Mar 31, 2016		Mar 31, 2015
Notes Payable under Revolving Credit Agreement	$	0.1	$	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	—		—
4.35% Senior Notes due February 15, 2025	5.4		—
7.375% Subordinated Debentures due February 27, 2054	2.8		2.8
Total Interest Paid	$	8.3	$	7.8