CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $) In Millions, unless otherwise specified	Total	COMMON STOCK	ADDITIONAL PAID-IN CAPITAL	NET UNREALIZED APPRECIATION ON INVESTMENTS AND DERIVATIVE INSTRUMENTS:	DEFINED BENEFIT PENSION AND POSTRETIREMENT PLANS:	CUMULATIVE FOREIGN CURRENCY TRANSLATION ADJUSTMENT:	Total accumulated other comprehensive income	RETAINED EARNINGS	TREASURY STOCK
Balance at beginning of period at Dec. 31, 2010		$ 0.6	$ 1,796.5	$ 218.3	$ (81.6)			$ 1,246.8	$ (720.1)
Cumulative effect of accounting change, net of taxes								(23.1)
Net appreciation during the period:
Net appreciation on available-for-sale securities and derivative instruments				41.0
Benefit (provision) for deferred income taxes				1.5
Unrealized gains arising during period, Net of Tax	64.3			42.5
Amount recognized as net periodic benefit cost during the period	5.1				5.1
Employee and director stock-based awards and other			(14.0)
Balance at beginning of period, as adjusted								1,223.7
Provision for deferred income taxes	(1.8)				(1.8)
Net shares reissued at cost under employee stock-based compensation plans									16.6
Net income (loss)	(2.9)							(2.9)
Total pension and postretirement benefits	3.3				3.3
Dividends to shareholders								(25.0)
Treasury stock issued for less than cost								(5.9)
Recognition of employee stock-based compensation								9.5
Balance at end of period at Jun. 30, 2011	2,461.5	0.6	1,782.5	260.8	(78.3)		182.5	1,199.4	(703.5)
Balance at beginning of period at Dec. 31, 2011	2,484.0	0.6	1,784.8	308.7	(86.8)	(11.5)		1,211.3	(723.1)
Net appreciation during the period:
Net appreciation on available-for-sale securities and derivative instruments				97.5
Benefit (provision) for deferred income taxes				(8.7)
Unrealized gains arising during period, Net of Tax	96.9			88.8
Amount recognized as net periodic benefit cost during the period	4.6				4.6
Amount recognized as cumulative foreign currency translation during the period	1.4					1.4
Shares purchased at cost									(10.0)
Employee and director stock-based awards and other			(2.6)
Balance at beginning of period, as adjusted								1,211.3
Provision for deferred income taxes	(1.6)				(1.6)
Provision for deferred income taxes	(0.5)					(0.5)
Net shares reissued at cost under employee stock-based compensation plans									9.3
Net income (loss)	70.5							70.5
Total pension and postretirement benefits	3.0				3.0
Total cumulative foreign currency translation adjustment	0.9					0.9
Dividends to shareholders								(27.0)
Treasury stock issued for less than cost								(3.8)
Recognition of employee stock-based compensation								4.4
Balance at end of period at Jun. 30, 2012	$ 2,617.5	$ 0.6	$ 1,782.2	$ 397.5	$ (83.8)	$ (10.6)	$ 303.1	$ 1,255.4	$ (723.8)