Notes Payable - Narrative (Details)	12 Months Ended
	Dec. 31, 2014
Discount Notes [Member]
Schedule of Short-term and Long-term Borrowings [Line Items]
Debt Instrument, original maturity period	1 year
Minimum [Member] | Medium-term Notes [Member]
Schedule of Short-term and Long-term Borrowings [Line Items]
Debt Instrument, original maturity period	0 years 6 months
Maximum [Member] | Medium-term Notes [Member]
Schedule of Short-term and Long-term Borrowings [Line Items]
Debt Instrument, original maturity period	15 years