Acquisitions - Kailua Portfolio Acquisition(Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				12 Months Ended			0 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 20, 2013 Property acre	Dec. 31, 2013
Business Acquisition, Pro Forma Information [Abstract]
Acquisition related costs	$ 0.1	$ 2.0	$ 1.5	$ 1.0	$ 0	$ 4.6	$ 6.8
Kailua Portfolio Acquisition
Business Acquisition [Line Items]
Fair value of consideration transferred								360.7
Number of real estate properties								43
Area of properties that are preservation-zone land								585
The purchase was funded with 1031 and 1033 proceeds								270.0
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Property, plant and equipment								367.7
Intangible assets								30.4
Total assets acquired								398.1
Intangible liabilities								26.0
Liabilities assumed								11.4
Total liabilities assumed								37.4
Net assets acquired								360.7
Business Acquisition, Pro Forma Information [Abstract]
Operating revenue						391.0	285.5
Income from continuing operations, after tax						23.3	14.2
Acquisition related costs						1.1
Net revenues since acquisition									0.8
Net earnings (loss) since acquisition									0.4
Bridge Loan | Kailua Portfolio Acquisition
Business Acquisition [Line Items]
Liabilities assumed in a business combination								60.0
Mortgages | Kailua Portfolio Acquisition
Business Acquisition [Line Items]
Liabilities assumed in a business combination								$ 12.0
Ground Lease | Kailua Portfolio Acquisition
Business Acquisition [Line Items]
Area of properties that is subject to ground leases								51
Retail | Kailua Portfolio Acquisition
Business Acquisition [Line Items]
Area of real building improvements owned by third-party								760,000