Stockholders' Equity - Net Transfers (To) From Navient (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Schedule of Transfers To and From Affiliate [Line Items]
Total capital contributions		$ 502,581,000		$ 546,081,000
Corporate push-down		(761,000)		4,977,000
Net change in income tax accounts		0		15,659,000
Net change in receivable/payable		(39,655,000)		(87,277,000)
Other		0		(31,000)
Total net transfers from the entity that is now a subsidiary of Navient	$ 0	462,165,000	$ 0	479,409,000
Loan origination activities
Schedule of Transfers To and From Affiliate [Line Items]
Total capital contributions		7,184,000		32,452,000
Loan sales
Schedule of Transfers To and From Affiliate [Line Items]
Total capital contributions		0		45,000
Corporate overhead activities
Schedule of Transfers To and From Affiliate [Line Items]
Total capital contributions		3,461,000		21,216,000
Other
Schedule of Transfers To and From Affiliate [Line Items]
Total capital contributions		$ 491,936,000		$ 492,368,000