Indebtedness - Senior Unsecured Notes Repurchases (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013
Unsecured Senior Notes [Line Items]
Principal Amount Repurchased	$ 29,824
Purchase Price	33,492
2017 Notes
Unsecured Senior Notes [Line Items]
Principal Amount Repurchased	430
Purchase Price	482
2017 II Notes
Unsecured Senior Notes [Line Items]
Principal Amount Repurchased	5,000
Purchase Price	5,300
2028 Notes
Unsecured Senior Notes [Line Items]
Principal Amount Repurchased	23,394
Purchase Price	26,547
2032 Notes
Unsecured Senior Notes [Line Items]
Principal Amount Repurchased	1,000
Purchase Price	$ 1,163