Investment Securities (Contractual maturities) (Details) (Subsidiaries GECC [Member], USD $) In Millions, unless otherwise specified	Mar. 31, 2013
Amortized Cost [Member]
Investment [Line Items]
Within one year	$ 2,969
After one year through five years	5,982
After five years through ten years	5,278
After ten years	17,833
Estimated Fair Value [Member]
Investment [Line Items]
Within one year	2,985
After one year through five years	6,233
After five years through ten years	5,769
After ten years	$ 21,578