Fair Value Measurements - Derivative Instrument Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Asset derivative instruments, at fair value	$ 1,053,502	$ 812,664
Fair value on a recurring basis | Quoted prices in active markets for identical assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Asset derivative instruments, at fair value	154,591	95,041
Liability derivative instruments, at fair value	121,381	71,107
Fair value on a recurring basis | Significant other observable inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Asset derivative instruments, at fair value	898,911	717,623
Liability derivative instruments, at fair value	405,220	241,589
Fair value on a recurring basis | Significant unobservable inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Asset derivative instruments, at fair value	0	0
Liability derivative instruments, at fair value	0	0
Fair value on a recurring basis | Fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Asset derivative instruments, at fair value	1,053,502	812,664
Liability derivative instruments, at fair value	$ 526,601	$ 312,696