Commitments and Contingencies (Details) $ in Millions	3 Months Ended
	Apr. 30, 2017 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Ground lease to a syndicate of banks - Synthetic Lease	99 years
Total Synthetic Lease term	7 years 6 months
Estimated construction period	2 years 6 months
Lease term - Synthetic Lease	5 years
Maximum number of renewal options	3
Lessee Leasing Arrangements, Operating Leases, Renewal Term	5 years
Expected construction costs for Synthetic lease financing	$ 380
Maximum residual value guarantee percentage	87.50%
Maximum total leverage ratio	3.5