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Debt Obligations, net (Schedule of Debt) (Details) - USD ($) | 1 Months Ended | 3 Months Ended | 7 Months Ended | 9 Months Ended |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Oct. 31, 2017 | Sep. 30, 2017 | Jan. 31, 2017 | Sep. 30, 2017 | Sep. 30, 2016 | Dec. 31, 2016 | Sep. 30, 2017 | Sep. 30, 2016 | Nov. 02, 2017 | Apr. 12, 2017 | Mar. 31, 2017 | Aug. 31, 2016 | Jun. 30, 2016 | Mar. 31, 2016
Debt Disclosure [Abstract] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Increase of weighted average debt maturity |  | 1 year 6 months |  |  |  |  |  |  |  |  |  |  |  |
Weighted average debt maturity |  | 4 years |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total debt obligations |  | $ 4,343,182,000 |  | $ 4,343,182,000 |  | $ 3,418,357,000 | $ 4,343,182,000 |  |  |  |  |  |  |
Debt discounts and deferred financing costs, net |  | (64,228,000) |  | (64,228,000) |  | (28,449,000) | (64,228,000) |  |  |  |  |  |  |
Total debt obligations, net |  | 4,278,954,000 |  | 4,278,954,000 |  | 3,389,908,000 | 4,278,954,000 |  |  |  |  |  |  |
Interest costs capitalized |  |  |  | 2,100,000 | $ 1,400,000 |  | 6,100,000 | $ 4,200,000 |  |  |  |  |  |
2015 $325 Million Secured Revolving Credit Facility |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount |  | 325,000,000 |  | 325,000,000 |  |  | 325,000,000 |  |  |  |  |  |  |
Total debt obligations |  | 0 |  | 0 |  | 0 | $ 0 |  |  |  |  |  |  |
Converted term loan, term |  |  |  |  |  |  | 1 year |  |  |  |  |  |  |
2015 $325 Million Secured Revolving Credit Facility | Minimum | Interest Rate Category One |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, margin (as a percent) |  |  |  |  |  |  | 1.25% |  |  |  |  |  |  |
2015 $325 Million Secured Revolving Credit Facility | Minimum | Interest Rate Category Two |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, margin (as a percent) |  |  |  |  |  |  | 2.25% |  |  |  |  |  |  |
2015 $325 Million Secured Revolving Credit Facility | Maximum | Interest Rate Category One |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, margin (as a percent) |  |  |  |  |  |  | 1.75% |  |  |  |  |  |  |
2015 $325 Million Secured Revolving Credit Facility | Maximum | Interest Rate Category Two |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, margin (as a percent) |  |  |  |  |  |  | 2.75% |  |  |  |  |  |  |
2015 $325 Million Secured Revolving Credit Facility | London Interbank Offered Rate (LIBOR) |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis point spread on variable interest rate (as a percent) |  |  |  |  |  |  | 2.50% |  |  |  |  |  |  |
2015 $325 Million Secured Revolving Credit Facility | London Interbank Offered Rate (LIBOR) | Minimum |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis point spread on variable interest rate (as a percent) |  |  |  |  |  |  | 1.00% |  |  |  |  |  |  |
2015 $325 Million Secured Revolving Credit Facility | Federal Funds Effective Swap Rate |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis point spread on variable interest rate (as a percent) |  |  |  |  |  |  | 0.50% |  |  |  |  |  |  |
2016 Senior Secured Credit Facility |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount |  | 400,000,000.0 |  | 400,000,000.0 |  |  | $ 400,000,000.0 |  |  |  |  | $ 500,000,000.0 | $ 450,000,000.0 |
Total debt obligations |  | $ 400,000,000 |  | 400,000,000 |  | $ 498,648,000 | $ 400,000,000 |  |  |  |  |  |  |
Basis point spread on variable interest rate (as a percent) |  |  |  |  |  |  | 1.00% |  |  |  |  |  |  |
2016 Senior Secured Credit Facility | London Interbank Offered Rate (LIBOR) |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis point spread on variable interest rate (as a percent) |  | 3.00% | 3.75% |  |  | 4.50% | 3.00% |  |  |  |  |  |  |
2016 Senior Secured Credit Facility | London Interbank Offered Rate (LIBOR) | Minimum |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis point spread on variable interest rate (as a percent) |  | 0.75% | 1.00% |  |  | 1.00% | 0.75% |  |  |  |  |  |  |
2016 Senior Secured Credit Facility | London Interbank Offered Rate (LIBOR) | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis point spread on variable interest rate (as a percent) |  |  |  |  |  |  | 2.00% |  |  |  |  |  |  |
2016 Senior Secured Credit Facility | Federal Funds Effective Swap Rate |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis point spread on variable interest rate (as a percent) |  |  |  |  |  |  | 0.50% |  |  |  |  |  |  |
Mortgages collateralized by net lease assets |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total debt obligations |  | $ 223,182,000 |  | $ 223,182,000 |  | $ 249,987,000 | $ 223,182,000 |  |  |  |  |  |  |
Weighted average interest rate (as a percent) |  | 5.20% |  | 5.20% |  |  | 5.20% |  |  |  |  |  |  |
Mortgages collateralized by net lease assets | Minimum |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stated interest rates (as a percent) |  | 4.851% |  | 4.851% |  |  | 4.851% |  |  |  |  |  |  |
Mortgages collateralized by net lease assets | Maximum |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stated interest rates (as a percent) |  | 7.26% |  | 7.26% |  |  | 7.26% |  |  |  |  |  |  |
Mortgages collateralized by net lease assets | London Interbank Offered Rate (LIBOR) | Property One |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Basis point spread on variable interest rate (as a percent) |  |  |  |  |  |  | 2.00% |  |  |  |  |  |  |
Total secured credit facilities and mortgages |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total debt obligations |  | $ 623,182,000 |  | $ 623,182,000 |  | 748,635,000 | $ 623,182,000 |  |  |  |  |  |  |
5.85% senior notes |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total debt obligations |  | $ 0 |  | $ 0 |  | 99,722,000 | $ 0 |  |  |  |  |  |  |
Stated interest rates (as a percent) |  | 5.85% |  | 5.85% |  |  | 5.85% |  |  |  | 5.85% |  |  |
9.00% senior notes |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total debt obligations |  | $ 0 |  | $ 0 |  | 275,000,000 | $ 0 |  |  |  |  |  |  |
Stated interest rates (as a percent) |  | 9.00% |  | 9.00% |  |  | 9.00% |  |  | 9.00% |  |  |  |
4.00% senior notes |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total debt obligations |  | $ 550,000,000 |  | $ 550,000,000 |  | 550,000,000 | $ 550,000,000 |  |  |  |  |  |  |
Stated interest rates (as a percent) |  | 4.00% |  | 4.00% |  |  | 4.00% |  |  |  |  |  |  |
7.125% senior notes |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total debt obligations |  | $ 300,000,000 |  | $ 300,000,000 |  | 300,000,000 | $ 300,000,000 |  |  |  |  |  |  |
Stated interest rates (as a percent) |  | 7.125% |  | 7.125% |  |  | 7.125% |  |  |  |  |  |  |
4.875% senior notes |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total debt obligations |  | $ 300,000,000 |  | $ 300,000,000 |  | 300,000,000 | $ 300,000,000 |  |  |  |  |  |  |
Stated interest rates (as a percent) |  | 4.875% |  | 4.875% |  |  | 4.875% |  |  |  |  |  |  |
5.00% senior notes |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total debt obligations |  | $ 770,000,000 |  | $ 770,000,000 |  | 770,000,000 | $ 770,000,000 |  |  |  |  |  |  |
Stated interest rates (as a percent) |  | 5.00% |  | 5.00% |  |  | 5.00% |  |  |  |  |  |  |
6.50% senior notes |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 275,000,000
Total debt obligations |  | $ 275,000,000 |  | $ 275,000,000 |  | 275,000,000 | $ 275,000,000 |  |  |  |  |  |  |
Stated interest rates (as a percent) |  | 6.50% |  | 6.50% |  |  | 6.50% |  |  |  |  |  |  | 6.50%
6.00% senior notes |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount |  |  |  |  |  |  |  |  |  |  | $ 375,000,000.0 |  |  |
Total debt obligations |  | $ 375,000,000 |  | $ 375,000,000 |  | 0 | $ 375,000,000 |  |  |  |  |  |  |
Stated interest rates (as a percent) |  | 6.00% |  | 6.00% |  |  | 6.00% |  |  |  | 6.00% |  |  |
4.625% senior notes |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount |  | $ 400,000,000.0 |  | $ 400,000,000.0 |  |  | $ 400,000,000.0 |  |  |  |  |  |  |
Total debt obligations |  | $ 400,000,000 |  | $ 400,000,000 |  | 0 | $ 400,000,000 |  |  |  |  |  |  |
Stated interest rates (as a percent) |  | 4.625% |  | 4.625% |  |  | 4.625% |  |  |  |  |  |  |
5.25% senior notes |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount |  | $ 400,000,000.0 |  | $ 400,000,000.0 |  |  | $ 400,000,000.0 |  |  |  |  |  |  |
Total debt obligations |  | $ 400,000,000 |  | $ 400,000,000 |  | 0 | $ 400,000,000 |  |  |  |  |  |  |
Stated interest rates (as a percent) |  | 5.25% |  | 5.25% |  |  | 5.25% |  |  |  |  |  |  |
3.125% senior convertible notes |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount |  | $ 250,000,000.0 |  | $ 250,000,000.0 |  |  | $ 250,000,000.0 |  |  |  |  |  |  |
Total debt obligations |  | $ 250,000,000 |  | $ 250,000,000 |  | 0 | $ 250,000,000 |  |  |  |  |  |  |
Stated interest rates (as a percent) |  | 3.125% |  | 3.125% |  |  | 3.125% |  |  |  |  |  |  |
Convertible debt, conversion ratio (in shares per par value) |  |  |  |  |  |  | 64.36 |  |  |  |  |  |  |
Convertible debt, conversion price (in dollars per share) |  | $ 15.54 |  | $ 15.54 |  |  | $ 15.54 |  |  |  |  |  |  |
Liability component of convertible debt |  | $ 221,800,000 |  | $ 221,800,000 |  |  | $ 221,800,000 |  |  |  |  |  |  |
Carrying value of equity component of convertible debt |  | 22,500,000 |  | 22,500,000 |  |  | 22,500,000 |  |  |  |  |  |  |
Unsecured Notes |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total debt obligations |  | 3,620,000,000 |  | 3,620,000,000 |  | 2,569,722,000 | 3,620,000,000 |  |  |  |  |  |  |
Trust preferred securities |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total debt obligations |  | $ 100,000,000 |  | $ 100,000,000 |  | $ 100,000,000 | $ 100,000,000 |  |  |  |  |  |  |
Basis point spread on variable interest rate (as a percent) |  |  |  |  |  |  | 1.50% |  |  |  |  |  |  |
Subsequent Event | 4.00% senior notes |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Make whole premium for early extinguishment of debt | $ 5,250,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Subsequent Event | 7.125% senior notes |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Make whole premium for early extinguishment of debt | $ 3,660,000 |  |  |  |  |  |  |  |  |  |  |  |  |
Subsequent Event | 3.125% senior convertible notes |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt instrument, face amount |  |  |  |  |  |  |  |  | $ 37,500,000 |  |  |  |  |

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- Definition Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt. + 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(22)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(16)) -URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03(16)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 + Details
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