Revenue from Contract with Customers Accounted for in Accordance with ASC 606 - Summary of Disaggregation of Revenue from Contracts Accounted Under ASC 606 with Customers (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation Of Revenue [Line Items]
Total Revenue	$ 100	$ 84	$ 198	$ 177
Federal Government [Member]
Disaggregation Of Revenue [Line Items]
Total Revenue	21	3	37	5
Guarantor Agencies [Member]
Disaggregation Of Revenue [Line Items]
Total Revenue	14	15	28	31
Other Institutions [Member]
Disaggregation Of Revenue [Line Items]
Total Revenue	4	3	6	6
State and Local Government [Member]
Disaggregation Of Revenue [Line Items]
Total Revenue	23	23	48	49
Tolling Authorities [Member]
Disaggregation Of Revenue [Line Items]
Total Revenue	13	16	27	42
Hospitals and Other Healthcare Providers [Member]
Disaggregation Of Revenue [Line Items]
Total Revenue	25	24	52	44
Federal Education Loans [Member]
Disaggregation Of Revenue [Line Items]
Total Revenue	35	19	64	39
Federal Education Loans [Member] | Federal Government [Member]
Disaggregation Of Revenue [Line Items]
Total Revenue	17	1	30	2
Federal Education Loans [Member] | Guarantor Agencies [Member]
Disaggregation Of Revenue [Line Items]
Total Revenue	14	15	28	31
Federal Education Loans [Member] | Other Institutions [Member]
Disaggregation Of Revenue [Line Items]
Total Revenue	4	3	6	6
Business Processing [Member]
Disaggregation Of Revenue [Line Items]
Total Revenue	65	65	134	138
Business Processing [Member] | Federal Government [Member]
Disaggregation Of Revenue [Line Items]
Total Revenue	4	2	7	3
Business Processing [Member] | State and Local Government [Member]
Disaggregation Of Revenue [Line Items]
Total Revenue	23	23	48	49
Business Processing [Member] | Tolling Authorities [Member]
Disaggregation Of Revenue [Line Items]
Total Revenue	13	16	27	42
Business Processing [Member] | Hospitals and Other Healthcare Providers [Member]
Disaggregation Of Revenue [Line Items]
Total Revenue	25	24	52	44
Federal Education Loan Asset Recovery Services [Member]
Disaggregation Of Revenue [Line Items]
Total Revenue	35	19	64	39
Federal Education Loan Asset Recovery Services [Member] | Federal Education Loans [Member]
Disaggregation Of Revenue [Line Items]
Total Revenue	35	19	64	39
Government Services [Member]
Disaggregation Of Revenue [Line Items]
Total Revenue	40	41	82	94
Government Services [Member] | Business Processing [Member]
Disaggregation Of Revenue [Line Items]
Total Revenue	40	41	82	94
Healthcare Services [Member]
Disaggregation Of Revenue [Line Items]
Total Revenue	25	24	52	44
Healthcare Services [Member] | Business Processing [Member]
Disaggregation Of Revenue [Line Items]
Total Revenue	$ 25	$ 24	$ 52	$ 44