Commitments and Contingencies - Additional Information (Detail)		3 Months Ended	12 Months Ended
	Mar. 31, 2016 USD ($) Loans Directors	Mar. 31, 2016 USD ($) Loans Installments	Dec. 31, 2015 USD ($)
Commitments And Contingencies [Line Items]
Commitments expiration period		4 years	4 years
Number of loans receivable | Loans	71	71
Percentage of compensation paid in cash	40.00%
Percentage of compensation in the form of deferred stock units	60.00%
Number of board of directors | Directors	8
Number of independent directors entitled to annual compensation | Directors	5
Number of equal quarterly installments | Installments		4
CT Investment Management Co LLC [Member] | Internal Revenue Service [Member]
Commitments And Contingencies [Line Items]
Income tax examinations, reserves	$ 0	$ 0
CT Investment Management Co LLC [Member] | New York State Division of Taxation and Finance [Member]
Commitments And Contingencies [Line Items]
Income tax examinations, reserves	0	0
Loans Receivable [Member]
Commitments And Contingencies [Line Items]
Unfunded loan commitments	965,140,000	$ 965,140,000	$ 700,658,000
Five Independent Board of Directors [Member]
Commitments And Contingencies [Line Items]
Annual cash compensation	125,000
Three Board of Directors [Member]
Commitments And Contingencies [Line Items]
Annual cash compensation	0
Chairperson of Audit Committee [Member]
Commitments And Contingencies [Line Items]
Annual cash compensation	$ 12,000