CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net income	$ 64,812	$ 166,531	$ 175,991	$ 186,185	$ 194,465	$ 194,216	$ 179,859	$ 174,959	$ 593,519	$ 743,499	$ 379,195
Other comprehensive income (loss), net of tax
Unrealized gains (losses) on derivatives, net of tax of $19,006, $5,452 and $(6,138), respectively									(21,408)	(30,300)	41,362
Realized (gains) losses on derivatives recognized in net income, net of tax of $(26,899), $230 and $8,815, respectively									63,687	(6,977)	(54,709)
Unrealized holding gains (losses) on available-for-sale securities, net of tax of $0, $0 and $648, respectively									0	0	(955)
Change in pension and postretirement benefit plan liability, net of tax of $(878), $11,128 and $(10,278), respectively									(4,175)	(16,693)	15,416
Other comprehensive income (loss) on investments in unconsolidated affiliates, net of tax of $145, $270 and $293, respectively									(970)	(1,505)	(1,632)
Total other comprehensive income (loss), net of tax									37,134	(55,475)	(518)
Comprehensive income									630,653	688,024	378,677
Less: Comprehensive income attributable to noncontrolling interests									236,704	363,093	124,589
Comprehensive income attributable to ONEOK									$ 393,949	$ 324,931	$ 254,088