Indebtedness - Senior Unsecured Notes Repurchases (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Unsecured Senior Notes [Line Items]
Principal Amount Repurchased	$ 29,824	$ 106,303
Purchase Price	33,492	110,613
2014 Notes
Unsecured Senior Notes [Line Items]
Principal Amount Repurchased	0	9,000
Purchase Price	0	9,439
2017 Notes
Unsecured Senior Notes [Line Items]
Principal Amount Repurchased	430	4,223
Purchase Price	482	4,632
2017 II Notes
Unsecured Senior Notes [Line Items]
Principal Amount Repurchased	5,000	0
Purchase Price	5,300	0
2028 Notes
Unsecured Senior Notes [Line Items]
Principal Amount Repurchased	23,394	69,680
Purchase Price	26,547	72,541
2032 Notes
Unsecured Senior Notes [Line Items]
Principal Amount Repurchased	1,000	23,400
Purchase Price	$ 1,163	$ 24,001