Debt (Tables)

3 Months Ended

Mar. 31, 2015

Debt Disclosure [Abstract]

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

The amortized cost of debt outstanding at March 31, 2015 and December 31, 2014 was:

(Dollars in Millions)	Mar 31, 2015		Dec 31, 2014
Senior Notes:
6.00% Senior Notes due November 30, 2015	$	—	$	249.5
6.00% Senior Notes due May 15, 2017	358.6		358.5
4.35% Senior Notes due February 15, 2025	247.3		—
7.375% Subordinated Debentures due February 27, 2054	144.1		144.1
Total Debt Outstanding	$	750.0	$	752.1

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, 2015 and 2014 was:

	Three Months Ended
(Dollars in Millions)	Mar 31, 2015			Mar 31, 2014
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			3.9
6.00% Senior Notes due May 15, 2017	5.6			5.5
4.35% Senior Notes due February 15, 2025	1.1			—
7.375% Subordinated Debentures due February 27, 2054	2.8			1.0
Interest Expense before Capitalization of Interest	13.4			10.6
Capitalization of Interest	(0.2		)	(0.3		)
Total Interest Expense	$	13.2		$	10.3

Schedule of Interest Paid [Table Text Block]

Interest paid, including facility fees, for the three months endedMarch 31, 2015 and 2014 was:

	Three Months Ended
(Dollars in Millions)	Mar 31, 2015		Mar 31, 2014
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	4.8		—
6.00% Senior Notes due May 15, 2017	—		—
4.35% Senior Notes due February 15, 2025	—		—
7.375% Subordinated Debentures due February 27, 2054	2.8		—
Total Interest Paid	$	7.8	$	0.2