Mortgage-Backed Securities - By Maturity (Details) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Mortgage Backed Securities By Maturity [Abstract]
Greater than five years and less than ten years	$ 12,436,000	$ 12,980,000
Greater than or equal to ten years	347,824,000	102,400,000
Total mortgage-backed securities	$ 360,260,273	$ 115,379,574

Investments in mortgage backed securities which are accounted for under the Fair Value Option. Such securities are reported at fair value; gains (losses) are included in earnings.

No definition available.

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