Accumulated Other Comprehensive Loss - Summary of Accumulated Other Comprehensive Loss (Detail) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2016
Sep. 30, 2015
Sep. 30, 2016
Sep. 30, 2015
Dec. 31, 2015
Dec. 31, 2014
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]            
Beginning Balance     $ 1,775,762 $ 1,164,734    
Total other comprehensive income (loss), net of tax $ 158 $ (17,973) (21,689) (22,703)    
Ending Balance 1,884,217 1,664,513 1,884,217 1,664,513    
Less: accumulated other comprehensive loss attributable to noncontrolling interest 906,685 810,712 906,685 810,712 $ 944,262 $ 530,586
Accumulated other comprehensive loss attributable to Pattern Energy 977,532   977,532   $ 831,500  
Foreign Currency [Member]            
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]            
Beginning Balance     (48,285) (19,338)    
Other comprehensive income (loss) before reclassifications     9,874 (21,900)    
Amounts reclassified from accumulated other comprehensive loss due to termination of interest rate derivatives       0    
Amounts reclassified from accumulated other comprehensive loss     0 0    
Total other comprehensive income (loss), net of tax     9,874 (21,900)    
Ending Balance (38,411) (41,238) (38,411) (41,238)    
Less: accumulated other comprehensive loss attributable to noncontrolling interest 0 0 0 0    
Accumulated other comprehensive loss attributable to Pattern Energy (38,411) (41,238) (38,411) (41,238)    
Effective Portion of Change in Fair Value of Derivatives [Member]            
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]            
Beginning Balance     (13,462) (26,672)    
Other comprehensive income (loss) before reclassifications     (30,990) (16,257)    
Amounts reclassified from accumulated other comprehensive loss due to termination of interest rate derivatives       11,221    
Amounts reclassified from accumulated other comprehensive loss     8,359 9,546    
Total other comprehensive income (loss), net of tax     (22,631) 4,510    
Ending Balance (36,093) (22,162) (36,093) (22,162)    
Less: accumulated other comprehensive loss attributable to noncontrolling interest (1,418) (950) (1,418) (950)    
Accumulated other comprehensive loss attributable to Pattern Energy (34,675) (21,212) (34,675) (21,212)    
Proportionate Share of Equity Investee's OCI [Member]            
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]            
Beginning Balance     (12,131) (7,903)    
Other comprehensive income (loss) before reclassifications     (11,684) (6,895)    
Amounts reclassified from accumulated other comprehensive loss due to termination of interest rate derivatives       0    
Amounts reclassified from accumulated other comprehensive loss     2,752 1,582    
Total other comprehensive income (loss), net of tax     (8,932) (5,313)    
Ending Balance (21,063) (13,216) (21,063) (13,216)    
Less: accumulated other comprehensive loss attributable to noncontrolling interest 0 0 0 0    
Accumulated other comprehensive loss attributable to Pattern Energy (21,063) (13,216) (21,063) (13,216)    
AOCI [Member]            
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]            
Beginning Balance     (73,878) (53,913)    
Other comprehensive income (loss) before reclassifications     (32,800) (45,052)    
Amounts reclassified from accumulated other comprehensive loss due to termination of interest rate derivatives       11,221    
Amounts reclassified from accumulated other comprehensive loss     11,111 11,128    
Total other comprehensive income (loss), net of tax     (21,689) (22,703)    
Ending Balance (95,567) (76,616) (95,567) (76,616)    
Less: accumulated other comprehensive loss attributable to noncontrolling interest (1,418) (950) (1,418) (950)    
Accumulated other comprehensive loss attributable to Pattern Energy $ (94,149) $ (75,666) $ (94,149) $ (75,666)