Transactions with Related Parties - Additional Information (Details)	1 Months Ended	9 Months Ended
	Oct. 31, 2014 USD ($)	Sep. 30, 2015 USD ($) Director	Dec. 31, 2014 USD ($)
ACA
Related Party Transaction [Line Items]
Percentage of management fees payable		8.33%
Management Fees
Related Party Transaction [Line Items]
Number of independent directors | Director		6
Management agreement initial expiration date		Feb. 23, 2016
Management agreement additional term of expiration		1 year
Prior notice for uncertain termination (in days)		180 days
Proportion of average annual management fee description		ACA must be provided 180 days prior notice of any such termination and will be paid a termination fee equal to four times the average annual management fee earned by ACA during the two year period immediately preceding termination, calculated as of the end of the most recently completed fiscal quarter prior to the date of termination.
Period of annual management fees earned (in years)		2 years
Management fee payable		$ 1,947,000	$ 3,198,000
Financial interest at an annual rate	$ 300,000
Management Fees | Company's Equity Up To $250 Million
Related Party Transaction [Line Items]
Management fee payable		$ 250,000,000
Management fee bases per annum		1.50%
Management Fees | Company's Equity In Excess Of $250 Million And Up To $500 Million
Related Party Transaction [Line Items]
Management fee payable		$ 500,000,000
Management fee bases per annum		1.10%
Management fee payable, minimum		$ 250,000,000
Management Fees | Company's Equity In Excess Of $500 Million And Up To $750 Million
Related Party Transaction [Line Items]
Management fee payable		$ 750,000,000
Management fee bases per annum		0.80%
Management fee payable, minimum		$ 500,000,000
Management Fees | Company's Equity In Excess Of $750 Million
Related Party Transaction [Line Items]
Management fee bases per annum		0.50%
Management fee payable, minimum		$ 750,000,000