Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Jun. 30, 2016	Mar. 31, 2016	Mar. 31, 2015
Subsequent Event [Line Items]
Other Underwriting Expense		$ 55.4	$ 56.0
Payments to Acquire Other Investments		10.9	$ 6.5
Subsequent Event [Member]
Subsequent Event [Line Items]
Proceeds from Divestiture of Interest in Subsidiaries and Affiliates	$ 2,600.0
Payments to Acquire Other Investments	(161.8)
Stock Repurchased and Retired During Period, Value	$ 287.0
Treasury Stock Acquired, Average Cost Per Share	$ 807
UNITED STATES
Subsequent Event [Line Items]
Stop Loss Limitation		45.0
Industry Loss Trigger on Industry Loss Warranty		15,000.0
UNITED STATES | Combination One [Member]
Subsequent Event [Line Items]
Stop Loss Limitation		75.0
Industry Loss Trigger on Industry Loss Warranty		40,000.0
UNITED STATES | Combination Two [Member]
Subsequent Event [Line Items]
Stop Loss Limitation		22.5
Industry Loss Trigger on Industry Loss Warranty		50,000.0
JAPAN
Subsequent Event [Line Items]
Stop Loss Limitation		25.0
Industry Loss Trigger on Industry Loss Warranty		$ 12,500.0
Common Stock [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Stock Repurchased and Retired During Period, Shares	356,423
Franklin Mutual Advisers [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Stock Repurchased and Retired During Period, Shares	325,000
Treasury Stock Acquired, Average Cost Per Share	$ 807