Including current and noncurrent portions, aggregate carrying amount of long-term borrowings as of the balance sheet date before deducting unamortized discount or premiums (if any). May include notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, which had initial maturities beyond one year or beyond the normal operating cycle, if longer.

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Senior Notes due May 1, 2016 - Additional Information (Detail) (Senior Notes due May 1, 2016, USD $) In Millions, unless otherwise specified	1 Months Ended		3 Months Ended		6 Months Ended
	Apr. 30, 2009	Apr. 17, 2006	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Senior Notes due May 1, 2016
Debt Instrument [Line Items]
Principal amount of senior notes		$ 125
Interest rate stated on senior notes		7.00%
Senior notes due date		May 01, 2016
Net proceeds from issuance of senior notes		123.5
Interest payment dates on senior notes		The interest payment dates on the Senior Notes are each May 1 and November 1.
Effective interest rate related to senior notes		7.17%
Interest expense on senior notes			2.0	2.0	4.1	4.1
Fair value of senior notes			124.7		124.7		117.6
Debt instrument, covenant compliance					As of June 30, 2011, the Company was in compliance with all such covenants.
Aggregate principal amount of senior notes repurchased from unaffiliated note holder	10.0
Repurchased senior notes	7.0
Pretax gain from repurchased of senior notes	2.9
Outstanding principal amount of senior notes			$ 115		$ 115