Indebtedness - Senior Unsecured Notes Repurchases (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013
Unsecured Senior Notes [Line Items]
Principal Amount Repurchased	$ 29,019
Purchase Price	32,588
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	23,019
Purchase Price	26,125
2032 Notes
Unsecured Senior Notes [Line Items]
Principal Amount Repurchased	1,000
Purchase Price	$ 1,163