4. Debt

Debt consists of the following:


(in millions)		September 30, 2016		December 31, 2015
Senior debentures maturing April 15, 2026	$	375.0	$	-
Senior debentures maturing June 15, 2021		-		300.0
Senior debentures maturing March 1, 2020		-		80.0
Senior debentures maturing October 15, 2025		74.6		74.6
Subordinated debentures maturing March 30, 2053		175.0		175.0
Subordinated debentures maturing February 3, 2027		59.7		59.7
FHLBB borrowings (secured)		125.0		125.0
Total principal debt	$	809.3	$	814.3
Unamortized debt issuance costs		(11.4)		(11.2)
Total	$	797.9	$	803.1

On April 8, 2016, the Company issued $375.0 million aggregate principal amount of 4.50% senior unsecured debentures due April 15, 2026. The senior debentures are subject to certain restrictive covenants, including limitations on the issuance or disposition of stock of restricted subsidiaries and limitations on liens. These debentures pay interest semi-annually.

Net proceeds from the issuance of the aforementioned debentures were $370.5 million. On May 21, 2016, the proceeds, together with cash on hand, were used to redeem the outstanding 7.50% notes due March 1, 2020 and 6.375% notes due June 15, 2021. The redemption of these notes resulted in a pre-tax loss of $86.1 million.

At September 30, 2016, the Company was in compliance with the covenants associated with its debt indentures and credit arrangements.