Leases - Summary of Lease Assets and Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Assets
Operating lease assets	$ 309,880	$ 0
Finance lease assets	$ 4,838
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssetsMember
Total lease assets	$ 314,718
Liabilities
Operating lease liabilities	333,964	$ 0
Finance lease liabilities	$ 5,078
Finance Lease, Liability, Statement of Financial Position [Extensible List]	faf:NotesAndContractsPayableMember
Total lease liabilities	$ 339,042