Summary Of Noncash Transactions (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Other Significant Noncash Transactions [Line Items]
Stock-based compensation not involving cash	$ 21,605	[1]	$ 14,954	[1]	$ 11,848	[1]
Commitments for low-income housing interests	29,759		36,722		137,817
Capitalized investment income	1,537		5,321		6,517
Debt assumed to acquire Family Heritage	20,000		0		0
Parent Company
Other Significant Noncash Transactions [Line Items]
Stock-based compensation not involving cash	21,605		14,954		11,848
Debt assumed to acquire Family Heritage	$ 20,000		$ 0		$ 0

[1] No stock-based compensation expense was capitalized in any period.