XML 59 R51.htm IDEA: XBRL DOCUMENT

Fair Value Disclosures - Additional Information (Detail) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Fair value, measurements, nonrecurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Estimated fair value of the debt	$ 319,400,000
US Treasury notes securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available-for-sale securities, debt maturities, period	June and September of 2013	March and June of 2013
Available-for-sale securities, amortized cost	160,000,000	224,900,000
Available-for-sale securities, gross unrealized gain (loss)	$ 0	$ 0

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References+ Details