- Proforma Consolidated Leverage Ratio (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013
Greater than or equal to 3.0x
Line of Credit Facility [Line Items]
Maximum aggregate principal amount of purchases, cancellations and redemptions of senior notes	$ 20
Greater than or equal to 2.5x
Line of Credit Facility [Line Items]
Maximum aggregate principal amount of purchases, cancellations and redemptions of senior notes	100
Greater than or equal to 2.0x
Line of Credit Facility [Line Items]
Maximum aggregate principal amount of purchases, cancellations and redemptions of senior notes	$ 200
Less than 2.0x
Line of Credit Facility [Line Items]
Less than 2.0x	no limit