Investments Composition of Fixed Maturities by Maturity (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014
Available for sale, cost
Less than one year	$ 1,882.0
One to five years	7,400.9
Five to ten years	2,862.0
Ten years or greater	85.4
Total	12,230.3	[1]
Available for sale, Fair value
Less than one year	1,920.2
One to five years	7,530.5
Five to ten years	2,919.2
Ten years or greater	93.6
Total	$ 12,463.5	[1]

[1] Excludes $35.1 million related to our open interest rate swap positions.