Off-Balance Sheet Risk and Guarantees, Concentrations of Credit Risk and Fair Value of Financial Instruments - Derivative Contracts (Details) - Dec. 31, 2015 - Foreign Exchange Forward € in Millions, £ in Millions, NOK in Millions, MYR in Millions, $ in Millions	USD ($)	MYR	EUR (€)	NOK	GBP (£)
Long
Derivative [Line Items]
Notional Amount	$ 216	MYR 175	€ 126	NOK 635	£ 115
Short
Derivative [Line Items]
Notional Amount	542	9	11	136	5
2016 | Long
Derivative [Line Items]
Notional Amount	212	175	89	604	113
2016 | Short
Derivative [Line Items]
Notional Amount	440	9	11	132	5
2017 | Long
Derivative [Line Items]
Notional Amount	4	0	37	31	2
2017 | Short
Derivative [Line Items]
Notional Amount	101	0	0	4	0
2018 | Short
Derivative [Line Items]
Notional Amount	$ 1	MYR 0	€ 0	NOK 0	£ 0