Debt - Schedule of Debt (Detail) - USD ($)
$ in Thousands |
3 Months Ended |
|
Mar. 31, 2018 |
Dec. 31, 2017 |
| Debt Instrument [Line Items] |
|
|
| Long-term debt, gross |
$ 2,478,559
|
$ 1,967,627
|
| Unamortized discount (premium), net |
(12,243)
|
(13,470)
|
| Unamortized financing costs |
(29,062)
|
(23,426)
|
| Total debt, net |
2,437,254
|
1,930,731
|
| Revolving credit facility |
248,000
|
0
|
| Current portion of long-term debt, net |
61,191
|
51,996
|
| Long-term debt, less current portion |
2,128,063
|
1,878,735
|
| Revolver credit facility [Member] |
|
|
| Debt Instrument [Line Items] |
|
|
| Long-term debt, gross |
$ 248,000
|
0
|
| Effective Interest Rate |
3.31%
|
|
| Maturity |
|
|
| Convertible senior notes 2020 [Member] |
|
|
| Debt Instrument [Line Items] |
|
|
| Long-term debt, gross |
$ 225,000
|
225,000
|
| Contractual Interest Rate |
4.00%
|
|
| Effective Interest Rate |
6.60%
|
|
| Maturity |
July 2020
|
|
| Unsecured senior notes 2024 [Member] |
|
|
| Debt Instrument [Line Items] |
|
|
| Long-term debt, gross |
$ 350,000
|
350,000
|
| Contractual Interest Rate |
5.88%
|
|
| Effective Interest Rate |
5.88%
|
|
| Maturity |
February 2024
|
|
| E1 Arrayan EKF term loan [Member] |
|
|
| Debt Instrument [Line Items] |
|
|
| Long-term debt, gross |
$ 96,974
|
99,112
|
| Contractual Interest Rate |
5.56%
|
|
| Effective Interest Rate |
5.56%
|
|
| Maturity |
March 2029
|
|
| Santa Isabel term loan [Member] |
|
|
| Debt Instrument [Line Items] |
|
|
| Long-term debt, gross |
$ 102,840
|
103,878
|
| Contractual Interest Rate |
4.565%
|
|
| Effective Interest Rate |
4.57%
|
|
| Maturity |
September 2033
|
|
| Ocotillo commercial term loan [Member] |
|
|
| Debt Instrument [Line Items] |
|
|
| Long-term debt, gross |
$ 289,201
|
289,339
|
| Contractual Interest Rate |
3.81%
|
|
| Effective Interest Rate |
4.06%
|
|
| Maturity |
June 2033
|
|
| El Arrayan commercial term loan [Member] |
|
|
| Debt Instrument [Line Items] |
|
|
| Long-term debt, gross |
$ 88,158
|
90,102
|
| Contractual Interest Rate |
4.25%
|
|
| Effective Interest Rate |
5.75%
|
|
| Maturity |
March 2029
|
|
| Spring Valley term loan [Member] |
|
|
| Debt Instrument [Line Items] |
|
|
| Long-term debt, gross |
$ 123,660
|
125,678
|
| Contractual Interest Rate |
4.06%
|
|
| Effective Interest Rate |
5.03%
|
|
| Maturity |
June 2030
|
|
| St. Joseph term loan [Member] |
|
|
| Debt Instrument [Line Items] |
|
|
| Long-term debt, gross |
$ 165,699
|
171,487
|
| Contractual Interest Rate |
3.36%
|
|
| Effective Interest Rate |
3.93%
|
|
| Maturity |
November 2033
|
|
| Western Interconnect [Member] |
|
|
| Debt Instrument [Line Items] |
|
|
| Long-term debt, gross |
$ 53,507
|
54,395
|
| Contractual Interest Rate |
4.31%
|
|
| Effective Interest Rate |
4.33%
|
|
| Maturity |
April 2027
|
|
| Meikle Wind Energy Limited Partnership [Member] |
|
|
| Debt Instrument [Line Items] |
|
|
| Long-term debt, gross |
$ 255,746
|
266,557
|
| Contractual Interest Rate |
3.23%
|
|
| Effective Interest Rate |
3.92%
|
|
| Maturity |
May 2024
|
|
| Futtsu [Member] |
|
|
| Debt Instrument [Line Items] |
|
|
| Long-term debt, gross |
$ 81,064
|
0
|
| Contractual Interest Rate |
1.07%
|
|
| Effective Interest Rate |
1.85%
|
|
| Maturity |
December 2033
|
|
| Ohorayama Term Loan [Member] |
|
|
| Debt Instrument [Line Items] |
|
|
| Long-term debt, gross |
$ 94,857
|
0
|
| Contractual Interest Rate |
0.87%
|
|
| Effective Interest Rate |
0.87%
|
|
| Maturity |
February 2036
|
|
| Tsugaru Construction Loan [Member] |
|
|
| Debt Instrument [Line Items] |
|
|
| Long-term debt, gross |
$ 50,862
|
0
|
| Contractual Interest Rate |
0.72%
|
|
| Effective Interest Rate |
0.72%
|
|
| Maturity |
March 2038
|
|
| Tsugaru Holdings Loan [Member] |
|
|
| Debt Instrument [Line Items] |
|
|
| Long-term debt, gross |
$ 60,912
|
0
|
| Contractual Interest Rate |
3.09%
|
|
| Effective Interest Rate |
3.09%
|
|
| Maturity |
July 2022
|
|
| Hatchet Ridge financing lease obligation [Member] |
|
|
| Debt Instrument [Line Items] |
|
|
| Long-term debt, gross |
$ 192,079
|
$ 192,079
|
| Contractual Interest Rate |
1.43%
|
|
| Effective Interest Rate |
1.43%
|
|
| Maturity |
December 2032
|
|