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Fair Value Disclosure of Financial Instruments - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions | 6 Months Ended |
--- | --- | ---
Jun. 30, 2017 | Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Preferred Stock, Redemption Price Per Share | $ 50.00 |
Fixed Rate Debt |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Notes Payable, fair value | $ 3,550.0 | $ 3,130.0
Notes Payable Excluding Interest Rate Swaps and Cap Agreements | 3,400.0 | 3,000.0
Variable Rate Debt |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Notes Payable, fair value | 1,175.1 | 1,511.3
Notes Payable Excluding Interest Rate Swaps and Cap Agreements | $ 1,170.0 | $ 1,500.0
Maximum [Member] | Conventional Variable Rate Debt [Member] |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Debt Renewal Period | 90 days |
Minimum [Member] | Conventional Variable Rate Debt [Member] |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Debt Renewal Period | 30 days |

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- Definition Fair value portion of notes payable. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19,20,22) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition The price per share at which the preferred stock of an entity that has priority over common stock in the distribution of dividends and in the event of liquidation of the entity is redeemed or may be called at. The redemption features of this preferred stock are solely within the control of the issuer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21475-112644 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21564-112644 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21488-112644 + Details
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