Short-Term and Long-Term Borrowings (Tables)

9 Months Ended

Sep. 30, 2016

Debt Disclosure [Abstract]

Schedule of lines of credit

(in thousands)	Line Limit		In Use on September 30, 2016		Restricted due to Outstanding Letters of Credit		Available on September 30, 2016		Available on December 31, 2015
Otter Tail Corporation Credit Agreement	$	150,000	$	—	$	—		$ 150 000	$	90,334
OTP Credit Agreement		170,000		37,173		50		132,777		148,694
Total	$	320,000	$	37,173	$	50	$	282,777	$	239,028

Schedule of short-term and long-term debt outstanding

September 30, 2016 (in thousands)	OTP		Otter Tail Corporation		Otter Tail Corporation Consolidated
Short-Term Debt	$	37,173	$	—	$	37,173
Long-Term Debt:
9.000% Notes, due December 15, 2016			$	52,330	$	52,330
Term Loan, LIBOR plus 0.90%, due February 5, 2018				50,000		50,000
Senior Unsecured Notes 5.95%, Series A, due August 20, 2017	$	33,000				33,000
Senior Unsecured Notes 4.63%, due December 1, 2021		140,000				140,000
Senior Unsecured Notes 6.15%, Series B, due August 20, 2022		30,000				30,000
Senior Unsecured Notes 6.37%, Series C, due August 20, 2027		42,000				42,000
Senior Unsecured Notes 4.68%, Series A, due February 27, 2029		60,000				60,000
Senior Unsecured Notes 6.47%, Series D, due August 20, 2037		50,000				50,000
Senior Unsecured Notes 5.47%, Series B, due February 27, 2044		90,000				90,000
North Dakota Development Note, 3.95%, due April 1, 2018				126		126
Partnership in Assisting Community Expansion (PACE) Note, 2.54%, due March 18, 2021				873		873
Total	$	445,000	$	103,329	$	548,329
Less:  Current Maturities net of Unamortized Debt Issuance Costs		32,958		52,532		85,490
Unamortized Long-Term Debt Issuance Costs		1,920		162		2,082
Total Long-Term Debt net of Unamortized Debt Issuance Costs	$	410,122	$	50,635	$	460,757
Total Short-Term and Long-Term Debt (with current maturities)	$	480,253	$	103,167	$	583,420

December 31, 2015 (in thousands)	OTP		Otter Tail Corporation		Otter Tail Corporation Consolidated
Short-Term Debt	$	21,006	$	59,666	$	80,672
Long-Term Debt:
9.000% Notes, due December 15, 2016			$	52,330	$	52,330
Senior Unsecured Notes 5.95%, Series A, due August 20, 2017	$	33,000				33,000
Senior Unsecured Notes 4.63%, due December 1, 2021		140,000				140,000
Senior Unsecured Notes 6.15%, Series B, due August 20, 2022		30,000				30,000
Senior Unsecured Notes 6.37%, Series C, due August 20, 2027		42,000				42,000
Senior Unsecured Notes 4.68%, Series A, due February 27, 2029		60,000				60,000
Senior Unsecured Notes 6.47%, Series D, due August 20, 2037		50,000				50,000
Senior Unsecured Notes 5.47%, Series B, due February 27, 2044		90,000				90,000
North Dakota Development Note, 3.95%, due April 1, 2018				182		182
Partnership in Assisting Community Expansion (PACE) Note, 2.54%, due March 18, 2021				977		977
Total	$	445,000	$	53,489	$	498,489
Less:  Current Maturities net of Unamortized Debt Issuance Costs				52,422		52,422
Unamortized Long-Term Debt Issuance Costs		2,099		122		2,221
Total Long-Term Debt net of Unamortized Debt Issuance Costs	$	442,901	$	945	$	443,846
Total Short-Term and Long-Term Debt (with current maturities)	$	463,907	$	113,033	$	576,940