Supplemental Disclosures Of Cash Flow Information (Summary Of Noncash Transactions) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Share-based compensation not involving cash	$ 14,954	[1]	$ 11,848	[1]	$ 9,860	[1]
Commitments for low-income housing interests	36,722		137,817		50,789
Capitalized investment income	5,321		6,517		7,345
Parent Company [Member]
Share-based compensation not involving cash	$ 14,954		$ 11,848		$ 9,860

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