Derivative Instruments and Hedging Activities Schedule of Interest Rate Swap Receivers (Details) - USD ($)	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
Notional	$ 49,205,497,000	$ 36,528,169,000	$ 31,226,878,000
Interest Rate Swap [Member] \| Short [Member]
Derivative [Line Items]
Notional	$ 8,788,761,000	$ 8,117,438,000
Weighted Average Variable Interest Rate	1.933%	2.612%
Weighted Average Fixed Interest Rate	2.262%	2.757%
Weighted Average Remaining Maturity	7 years 7 months 9 days	5 years 2 months 19 days
Interest Rate Swap [Member] \| Derivative Maturity Within One Year From Balance Sheet Date [Member] \| Short [Member]
Derivative [Line Items]
Notional	$ 250,000,000	$ 0
Weighted Average Variable Interest Rate	1.953%	0.00%
Weighted Average Fixed Interest Rate	2.258%	0.00%
Weighted Average Remaining Maturity	1 hour	0 days
Interest Rate Swap [Member] \| Derivative Maturity Over One And Within Two Years From Balance Sheet Date [Member] \| Short [Member]
Derivative [Line Items]
Notional	$ 915,000,000	$ 250,000,000
Weighted Average Variable Interest Rate	1.894%	2.469%
Weighted Average Fixed Interest Rate	2.516%	2.258%
Weighted Average Remaining Maturity	1 year 1 month 6 days	1 year 21 days
Interest Rate Swap [Member] \| Derivative Maturity Over Two And Within Three Years From Balance Sheet Date [Member] \| Short [Member]
Derivative [Line Items]
Notional	$ 0	$ 2,477,438,000
Weighted Average Variable Interest Rate	0.00%	2.538%
Weighted Average Fixed Interest Rate	0.00%	2.736%
Weighted Average Remaining Maturity	0 years	2 years 2 months 26 days
Interest Rate Swap [Member] \| Derivative Maturity Over Three And Within Four Years From Balance Sheet Date [Member] \| Short [Member]
Derivative [Line Items]
Notional	$ 0	$ 800,000,000
Weighted Average Variable Interest Rate	0.00%	2.653%
Weighted Average Fixed Interest Rate	0.00%	2.975%
Weighted Average Remaining Maturity	0 years	3 years 4 months 20 days
Interest Rate Swap [Member] \| Derivative Maturity Over Four Years From Balance Sheet Date [Member] \| Short [Member]
Derivative [Line Items]
Notional	$ 7,623,761,000	$ 4,590,000,000
Weighted Average Variable Interest Rate	1.937%	2.653%
Weighted Average Fixed Interest Rate	2.232%	2.757%
Weighted Average Remaining Maturity	8 years 7 months 20 days	7 years 4 months 13 days

Average fixed interest rate related to the group of interest rate derivatives.

No definition available.

Name:	us-gaap_DerivativeAverageFixedInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Average remaining period until maturity of the derivative contract, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeAverageRemainingMaturity1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Average variable interest rate related to the group of interest rate derivatives.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeAverageVariableInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Nominal or face amount used to calculate payment on derivative.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5579245-113959

+ Details

Name:	us-gaap_DerivativeNotionalAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateSwapMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PositionAxis=us-gaap_ShortMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	two_DerivativeByMaturityAxis=two_DerivativeMaturityWithinOneYearFromBalanceSheetDateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	two_DerivativeByMaturityAxis=two_DerivativeMaturityOverOneAndWithinTwoYearsFromBalanceSheetDateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	two_DerivativeByMaturityAxis=two_DerivativeMaturityOverTwoAndWithinThreeYearsFromBalanceSheetDateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	two_DerivativeByMaturityAxis=two_DerivativeMaturityOverThreeAndWithinFourYearsFromBalanceSheetDateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	two_DerivativeByMaturityAxis=two_DerivativeMaturityOverFourYearsFromBalanceSheetDateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: