Litigation and Regulatory Matters - Additional Information (Detail)	1 Months Ended
	Mar. 31, 2017 USD ($)
Loss Contingencies [Line Items]
Estimate of possible loss	$ 390,000,000
Consumer Relief through Receivable Modification Programs [Member] | Foreclosure Litigation [Member]
Loss Contingencies [Line Items]
Litigation settlement amount	$ 370,000,000