Summary of Significant Accounting Policies - Debt Issuance Costs (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015
Amortization of deferred financing fees
Amortization expense in 2017	$ 5,829
Amortization expense in 2018	4,084
Amortization expense in 2019	3,225
Amortization expense in 2020	1,810
Amortization expense in 2021	1,695
Amortization expense thereafter	17,069
Unsecured Term Loans, Senior Notes, and Mortgage Notes Payable
Indebtedness
Deb issuance costs, gross	49,331	$ 39,497
Accumulated amortization, debt issuance costs gross	17,560	15,608
Revolving Credit Facility
Indebtedness
Debt issuance costs, line of credit arrangements, gross	10,980	10,980
Accumulated amortization, debt issuance costs gross	$ 9,039	7,174
Assets \| Accounting Standards Update 2015-03 \| Unsecured Term Loan
Indebtedness
Debt issuance costs, net		(3,695)
Assets \| Accounting Standards Update 2015-03 \| Senior Unsecured Notes
Indebtedness
Debt issuance costs, net		(16,530)
Assets \| Accounting Standards Update 2015-03 \| Secured Debt And Capital Lease
Indebtedness
Debt issuance costs, net		(3,664)
Debt \| Accounting Standards Update 2015-03 \| Unsecured Term Loan
Indebtedness
Debt issuance costs, net		3,695
Debt \| Accounting Standards Update 2015-03 \| Senior Unsecured Notes
Indebtedness
Debt issuance costs, net		16,530
Debt \| Accounting Standards Update 2015-03 \| Secured Debt And Capital Lease
Indebtedness
Debt issuance costs, net		$ 3,664

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Represents the amount of amortization of deferred financing fees expected to be recognized after the fifth succeeding fiscal year.

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Represents the amount of amortization of deferred financing fees expected to be recognized during year five of the five succeeding fiscal years.

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Represents the amount of amortization of deferred financing fees expected to be recognized during year four of the five succeeding fiscal years.

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Represents the amount of amortization of deferred financing fees expected to be recognized during year one of the five succeeding fiscal years.

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Represents the amount of amortization of deferred financing fees expected to be recognized during year three of the five succeeding fiscal years.

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Represents the amount of amortization of deferred financing fees expected to be recognized during year two of the five succeeding fiscal years.

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Amount of accumulated amortization of debt issuance costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28555-108399

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Amount, before accumulated amortization, of debt issuance costs related to line of credit arrangements. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section S45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=68176171&loc=SL68176184-208336

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Amount, before accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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