Mortgage-Backed Securities - Narrative (Details) - USD ($)	Jun. 30, 2017	Dec. 31, 2016
Mortgage Backed Securities [Abstract]
Unpledged Mortgage Backed Securities	$ 286,880,000	$ 49,884,000
Unsettled Securities Purchases Included in Unpledged Securities	$ 272,300,000

Investments in mortgage backed securities for which the Fair Value Option has been elected that are unencumbered at the balance sheet date. Such securities are reported at fair value; gains (losses) are included in earnings.

No definition available.

Name:	orc_MortgageBackedSecuritiesAtFairValueUnpledged
Namespace Prefix:	orc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant