Preferred Stock (Details Textual) $ / shares in Units, $ in Thousands, $ in Millions								3 Months Ended					6 Months Ended
	May 20, 2019 USD ($)	Mar. 01, 2019 USD ($)	Feb. 25, 2019 USD ($) $ / shares shares	Feb. 25, 2019 CAD ($)	Nov. 26, 2018 USD ($)	Aug. 29, 2018 USD ($)	May 25, 2018 USD ($)	Jun. 30, 2019 USD ($) shares	Jun. 30, 2019 CAD ($) shares	Mar. 31, 2019 USD ($)	Mar. 31, 2019 CAD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) shares	Jun. 30, 2018 USD ($)	Dec. 31, 2018 shares
Preferred Stock, Shares Issued | shares								350,000	350,000				350,000		350,000
Dividends, Preferred Stock, Paid-in-kind | $								$ 6,541				$ 4,830	$ 12,970	$ 4,830
Redeemable Preferred Stock [Member]
Convertible Preferred Stock, Shares Issued upon Conversion | shares								11,525,181	11,525,181				11,525,181
Dividends, Preferred Stock, Paid-in-kind | $	$ 6,541	$ 6,430			$ 6,317	$ 6,211	$ 4,832
Subsidiary redeemable preferred stock [Member]
Convertible Preferred Stock, Shares Issued upon Conversion | shares								302,480	302,480				302,480
SemCAMS Midstream [Member] | Subsidiary redeemable preferred stock [Member]
Preferred Stock, Shares Issued | shares			300,000
Preferred stock per share annualized dividend			$ 87.50
Proceeds from Issuance of Redeemable Preferred Stock			$ 223,800	$ 293.7
Payments of Stock Issuance Costs			$ 4,800	$ 6.3
Dividends, Preferred Stock, Paid-in-kind								$ 5,100	$ 6.6	$ 1,900	$ 2.5
Canada, Dollars | SemCAMS Midstream [Member] | Subsidiary redeemable preferred stock [Member]
Shares Issued, Price Per Share			$ 1,000
Preferred Stock, Redemption Price Per Share			1,100
United States of America, Dollars | SemCAMS Midstream [Member] | Subsidiary redeemable preferred stock [Member]
Shares Issued, Price Per Share			764
Preferred Stock, Redemption Price Per Share			$ 840