Shareholders' Equity - Conversion of Series D Convertible Units into Class A Units (Details) - Series D Convertible Units $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2016 USD ($) $ / shares shares	Dec. 31, 2015 shares
Class of Stock [Line Items]
Percentage of distributions claimed on operating partnership units	70.00%
Period after issuance for eligibility to participate in operating partnership distributions	30 months
Conversion requirements, adjusted funds from operations per share (in USD per share) | $ / shares	$ 0.80
Conversion requirements, average price per common share (in USD per share) | $ / shares	$ 18.00
Noncash charge related to contingent beneficial conversion on convertible units | $	$ 4.8
AH LLC
Class of Stock [Line Items]
Ownership units owned (in shares)	0	4,375,000
Operating Partnership
Class of Stock [Line Items]
Ownership units owned (in shares)	8,750,000
Operating Partnership | AH LLC
Class of Stock [Line Items]
Conversion ratio of convertible units	1
Ownership units owned (in shares)	0	4,375,000