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Fair Value of Derivatives and Financial Instruments (Textual) (Details) | 3 Months Ended |
--- | --- | ---
Mar. 31, 2019 USD ($) Contract $ / shares | Dec. 31, 2018 USD ($)
Derivative |  |
Preferred Stock, Redemption Price Per Share | $ / shares | $ 50.00 |
Preferred Stock, Redemption Date | Oct. 01, 2026 |
Designated as Hedging Instrument | Interest Rate Swap |  |
Derivative |  |
Derivative, Number of Instruments Held | Contract | 4 |
Derivative, Notional Amount | $ 300,000,000 |
Designated as Hedging Instrument | Interest Expense |  |
Derivative |  |
Change in fair value of interest rate derivatives included in AOCI and expected to be reclassified in the next 12 months | 1,600,000 |
Fixed Rate Debt |  |
Derivative |  |
Notes Payable Excluding Interest Rate Swaps and Cap Agreements | 3,600,000,000 | $ 3,100,000,000
Notes Payable, Fair Value Disclosure | 3,700,000,000 | 3,100,000,000
Floating Rate Debt [Member] |  |
Derivative |  |
Notes Payable Excluding Interest Rate Swaps and Cap Agreements | 1,000,000,000 | 1,100,000,000
Notes Payable, Fair Value Disclosure | $ 1,000,000,000 | 1,100,000,000
Minimum [Member] | Conventional Variable Rate Debt [Member] |  |
Derivative |  |
Debt Renewal Period | 30 days |
Maximum [Member] | Conventional Variable Rate Debt [Member] |  |
Derivative |  |
Debt Renewal Period | 90 days |
Fair Value, Measurements, Recurring [Member] |  |
Derivative |  |
Embedded Derivative, Fair Value of Embedded Derivative Asset | $ 18,100,000 | 18,600,000
Interest Rate Derivative Assets, at Fair Value | 2,500,000 | 3,700,000
Interest Rate Derivative Liabilities, at Fair Value | 0 | $ 5,300,000
net liability position [Member] |  |
Derivative |  |
Credit Risk Related Contingent Features Termination Value | $ 0 |

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- Definition Aggregate notional amount specified by the derivative(s). Expressed as an absolute value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column B + Details
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