Fair Value of Debt (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013
Fair Value Measurements [Line Items]
Fair value of debt	$ 1,224,232
Quoted Prices In Active Markets (Level 1)
Fair Value Measurements [Line Items]
Fair value of debt	844,020
Significant Other Observable Inputs (Level 2)
Fair Value Measurements [Line Items]
Fair value of debt	$ 380,212

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

No definition available.

Name:	us-gaap_LongTermDebtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant