Commitments and Contingencies - Contractual Commitments - Land Pipeline (Details) $ / shares in Units, $ in Thousands		12 Months Ended
	Feb. 10, 2017 USD ($) a $ / shares $ / a	Dec. 31, 2014 USD ($) a $ / a	Feb. 16, 2017 a	Dec. 31, 2016 a
Subsequent Event [Member]
Loss Contingencies [Line Items]
Area of a real estate property	2,210
Contract Amount | $	$ 82,931
Price per Acre | $ / a	38,000
Subsequent Event [Member] | Minto Communities
Loss Contingencies [Line Items]
Percentage area of real estate property	16.00%
Area of a real estate property	1,581
Sales price | $	$ 27,200
Sales price per acre | $ / a	17,200
Gain (loss) on disposal | $	$ 20,000
Gain (loss) on sale of building per share after tax | $ / shares	$ 2.19
Commercial | Subsequent Event [Member]
Loss Contingencies [Line Items]
Area of a real estate property	35
Contract Amount | $	$ 14,000
Price per Acre | $ / a	400,000
Commercial Tranche Two | Subsequent Event [Member]
Loss Contingencies [Line Items]
Area of a real estate property	4
Contract Amount | $	$ 1,175
Price per Acre | $ / a	294,000
Commercial Tranche Three | Subsequent Event [Member]
Loss Contingencies [Line Items]
Area of a real estate property	6
Contract Amount | $	$ 1,556
Price per Acre | $ / a	259,000
Mixed-Use Retail | Subsequent Event [Member]
Loss Contingencies [Line Items]
Area of a real estate property	22
Contract Amount | $	$ 5,574
Price per Acre | $ / a	253,000
Mixed-Use Retail Tranche Two | Subsequent Event [Member]
Loss Contingencies [Line Items]
Area of a real estate property	82
Contract Amount | $	$ 20,187
Price per Acre | $ / a	246,000
Residential | Subsequent Event [Member]
Loss Contingencies [Line Items]
Area of a real estate property	7
Contract Amount | $	$ 1,140
Price per Acre | $ / a	163,000
Commercial Tranche Four | Subsequent Event [Member]
Loss Contingencies [Line Items]
Area of a real estate property	28
Contract Amount | $	$ 3,215
Price per Acre | $ / a	115,000
Age Restricted Residential [Member] | Subsequent Event [Member]
Loss Contingencies [Line Items]
Area of a real estate property	1,686
Contract Amount | $	$ 31,360
Price per Acre | $ / a	19,000
Single-tenant | Subsequent Event [Member]
Loss Contingencies [Line Items]
Area of a real estate property	194
Contract Amount | $	$ 3,324
Price per Acre | $ / a	17,000
Single-tenant Tranche Two | Subsequent Event [Member]
Loss Contingencies [Line Items]
Area of a real estate property	146
Contract Amount | $	$ 1,400
Price per Acre | $ / a	10,000
Land [Member]
Loss Contingencies [Line Items]
Area of a real estate property		99.7		9,800
Sales price | $		$ 8,807
Sales price per acre | $ / a		88,000
Land [Member] | Subsequent Event [Member]
Loss Contingencies [Line Items]
Area of a real estate property	8,200
2017 Disposals | Sold | Subsequent Event [Member] | Minto Communities
Loss Contingencies [Line Items]
Area of a real estate property			1,581