Non-Agency Securities, Trading - Continuous Unrealized Loss Position (Details) $ in Thousands	Mar. 31, 2016 USD ($)
Fair Value
Less than 12 Months	$ 103,211
12 Months or More	0
Total	103,211
Unrealized Losses
Less than 12 Months	(430)
12 Months or More	0
Total	$ (430)

Trading Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss

No definition available.

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Trading Securities, Continuous Unrealized Loss Position, Accumulated Loss

No definition available.

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Trading Securities, Continuous Unrealized Loss Position, Aggregate Loss [Abstract]

No definition available.

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Trading Securities, Continuous Unrealized Loss Position, Fair Value

No definition available.

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Trading Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]

No definition available.

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Trading Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss

No definition available.

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Trading Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value

No definition available.

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Trading Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value

No definition available.

Name:	arr_TradingSecuritiesContinuousUnrealizedLossPositionTwelveMonthsorLongerFairValue
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Data Type:	xbrli:monetaryItemType
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Period Type:	instant