Income Taxes - Components of deferred tax assets and liabilities (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Federal loss carryforwards	$ 0	$ 23,000,000
State loss carryforwards and credits	48,000,000	39,000,000
Reserves and allowances	17,000,000	36,000,000
Exit cost liability	10,000,000	10,000,000
Accrued legal and regulatory matters	6,000,000	46,000,000
Other accrued liabilities	17,000,000	24,000,000
Other	4,000,000	0
Gross deferred tax assets	102,000,000	178,000,000
Valuation allowance	(78,000,000)	(44,000,000)
Deferred tax assets, net of valuation allowance	24,000,000	134,000,000
Deferred tax liabilities:
Mortgage servicing rights(1)	20,000,000	234,000,000
Other	4,000,000	1,000,000
Deferred tax liabilities	24,000,000	235,000,000
Net deferred tax liability	$ 0	$ 101,000,000