Leases - Summary of Recapture Rights Exercised by the Company (Detail)	12 Months Ended
	Dec. 31, 2017
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type, Percentage	100.00%
Anchorage, AK [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type, Percentage	100.00%
Notice Date(s)	2017-12
Braintree, MA [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type, Percentage	100.00%
Notice Date(s)	2015-11
Boca Raton, FL [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type, Percentage	100.00%
Notice Date(s)	2017-12
Honolulu, HI [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type, Percentage	100.00%
Notice Date(s)	2015-12
Westminster, CA [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type, Percentage	100.00%
Notice Date(s)	2017-12
Memphis, TN [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type, Percentage	100.00%
Notice Date(s)	2015-12
Hicksville, NY [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type, Percentage	100.00%
Notice Date(s)	2017-12
San Antonio, TX [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type	Auto center
Notice Date(s)	2016-03
Orland Park, IL [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type, Percentage	100.00%
Notice Date(s)	2017-12
Bowie, MD [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type	Auto center
Notice Date(s)	2016-05
Florissant, MO [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type	Out parcel
Notice Date(s)	2017-12
Hagerstown, MD [member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type	Auto center
Notice Date(s)	2016-05
Salem, NH [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type	Out parcel
Notice Date(s)	2017-12
Albany, NY [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type	Auto center
Notice Date(s)	2016-05
Fairfield, CA [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type	Partial
Notice Date(s)	2017-12
Fairfax, VA [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type	Partial + auto center
Notice Date(s)	2016-05
Las Vegas N V
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type	Partial
Notice Date(s)	2017-12
Wayne, NJ [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type	Partial + auto center
Notice Date(s)	2016-05
Plantation, FL [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type	Partial
Notice Date(s)	2017-12
Ft. Wayne, IN Property 1 [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type	Out parcel
Notice Date(s)	2017-09
Yorktown Heights [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type	Partial
Notice Date(s)	2017-12
Orlando, FL [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type, Percentage	100.00%
Notice Date(s)	2016-07
Austin, TX [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type, Percentage	100.00%
Notice Date (s)	December 2017 / September2017
Anderson, SC [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type, Percentage	100.00%
Notice Date (s)	April 2017 / July 2016
North Little Rock, AR [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type	Auto Center
Notice Date(s)	2017-09
West Jordan, UT [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type	Partial + auto center
Notice Date(s)	2016-07
Madison, WI [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type	Partial
Notice Date(s)	2016-07
St. Clair Shores, MI [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type, Percentage	100.00%
Notice Date(s)	2017-09
North Hollywood, CA [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type	Partial
Notice Date(s)	2016-07
Redmond WA [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type	Auto Center
Notice Date(s)	2017-09
Warwick, RI [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type	Auto center
Notice Date(s)	2016-10
Temecula, CA [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type	Partial
Notice Date(s)	2017-06
Rehoboth Beach, DE [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type	Partial
Notice Date(s)	2016-10
Roseville, CA [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type	Auto center
Notice Date(s)	2017-06
Charleston, SC [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type, Percentage	100.00%
Notice Date (s)	April 2017 / October 2016
North Riverside, IL [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type	Partial
Notice Date(s)	2017-06
West Hartford, CT [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type, Percentage	100.00%
Notice Date(s)	2016-10
Watchung, NJ [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type, Percentage	100.00%
Notice Date(s)	2017-06
St. Petersburg, FL [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type, Percentage	100.00%
Notice Date(s)	2016-10
Canton, OH [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type	Partial
Notice Date(s)	2017-06
Roseville, MI [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type	Partial
Notice Date(s)	2016-11
Dayton, OH [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type	Auto center
Notice Date(s)	2017-06
Troy, MI [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type	Partial
Notice Date(s)	2016-11
Santa Monica, CA [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type, Percentage	100.00%
Notice Date(s)	2016-12
San Diego C A
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type, Percentage	100.00%
Notice Date(s)	2017-04
Santa Cruz, CA [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type	Partial
Notice Date(s)	2016-12
Aventura, FL [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type, Percentage	100.00%
Notice Date(s)	2017-04
Guaynabo, PR [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type	Partial
Notice Date(s)	2016-12
Hialeah, FL [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type, Percentage	100.00%
Notice Date(s)	2017-04
Saugus, MA [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type	Partial
Notice Date(s)	2016-12
Carson, CA [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type, Percentage	100.00%
Notice Date (s)	April 2017 / December 2016
Valley View, TX [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type, Percentage	100.00%
Notice Date(s)	2017-04
North Miami, FL [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type, Percentage	100.00%
Notice Date(s)	2017-03
Cockeysville, MD [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type	Partial
Notice Date(s)	2017-03
Olean, NY [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type	Partial
Notice Date(s)	2017-03
Ft. Wayne, IN Property 2 [Member]
Property Subject to or Available for Operating Lease [Line Items]
Recapture Type	Out parcel
Notice Date(s)	2016-07