Debt, Financing Arrangements, and Leases (Details) - USD ($)		12 Months Ended
	Apr. 15, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Aug. 24, 2018	Jul. 13, 2018	May 02, 2018	Apr. 03, 2017	Oct. 01, 2009
Debt Instrument [Line Items]
Debt issuance costs		$ 4,507,000	$ 2,415,000
Debt Instrument, Unamortized Discount, Noncurrent		4,325,000	963,000
Long-term debt due within one year		0	249,874,000
Total long-term debt less current portion		576,168,000	331,748,000
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2019		1,942,000
2020		1,968,000
2021		1,920,000
2022		1,909,000
2023		1,832,000
Thereafter		11,508,000
Operating Leases, Future Minimum Payments Due		21,079,000
Lessee, Operating Lease, Term of Contract									10 years
Lessee, Operating Lease, Renewal Term							10 years
Operating Leases, Rent Expense		$ 2,800,000	3,500,000	$ 2,700,000
4% Senior Unsecured Notes Due 2027 [Member]
Debt Instrument [Line Items]
Issuance of debt					$ 250,000,000
Debt Instrument, Interest Rate, Stated Percentage		4.00%
6.05% Senior Unsecured Notes due 2018 [Member]
Debt Instrument [Line Items]
Long-term Debt		$ 0	250,000,000
7.125 percent unsecured debentures due 2025 [Member]
Debt Instrument [Line Items]
Long-term Debt		85,000,000	85,000,000
4.0% unsecured debentures due 2027 [Member]
Debt Instrument [Line Items]
Long-term Debt		500,000,000	$ 250,000,000
Issuance of debt								$ 250,000,000
5.95 percent senior unsecured notes due 2017 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.95%
Extinguishment of Debt, Amount	$ 185,000,000,000
Line of Credit [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity						$ 500,000,000
Line of Credit [Member] | Williams Companies Inc [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity						4,500,000,000
Additional Amount By Which Credit Facility Can Be Increased						500,000,000
Long-term Line of Credit		160,000,000
Swing Line Loan | Williams Companies Inc [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity						200,000,000
Commercial Paper [Member] | Williams Companies Inc [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity						4,000,000,000
Commercial Paper		0
Letter of Credit [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity						500,000,000
Letters of Credit Outstanding, Amount		$ 0
Letter of Credit [Member] | Williams Companies Inc [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity						$ 1,000,000,000