Escrow Deposits, Like-Kind Exchange Deposits And Trust Assets (Details) (USD $)	Mar. 31, 2012	Dec. 31, 2011
Escrow Deposits, Like-Kind Exchange Deposits And Trust Assets [Abstract]
Escrow deposits	$ 4,100,000,000	$ 3,100,000,000
Escrow deposits held at federal savings bank subsidiary	1,200,000,000	900,000,000
Trust assets	3,000,000,000	2,800,000,000
Like-kind exchange funds	$ 721,500,000	$ 564,700,000