Derivative Instruments (Details 2) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014
Derivative [Line Items]
Notional Amount		$ 134,700	$ 66,600
Fair Value		2,501	2,458
Bank of America, N.A. [Member]
Derivative [Line Items]
Notional Amount		17,000	8,700
Fair Value		5	439
Credit Suisse International [Member]
Derivative [Line Items]
Notional Amount		12,000	27,500
Fair Value		167	1,193
Societe Generale [Member]
Derivative [Line Items]
Notional Amount		80,800	25,400
Fair Value		1,347	756
Barclays Bank PLC [Member]
Derivative [Line Items]
Notional Amount		7,600	5,000
Fair Value		137	70
Citigroup Inc [Member]
Derivative [Line Items]
Notional Amount		17,300	0
Fair Value		$ 845	$ 0
Moody's [Member] | Bank of America, N.A. [Member]
Derivative [Line Items]
Credit Rating	[1]	A1
Moody's [Member] | Societe Generale [Member]
Derivative [Line Items]
Credit Rating	[1]	A2
Moody's [Member] | Barclays Bank PLC [Member]
Derivative [Line Items]
Credit Rating	[1]	A2
Moody's [Member] | Credit Suisse International [Member]
Derivative [Line Items]
Credit Rating	[1]	A1-
Moody's [Member] | Citigroup Inc [Member]
Derivative [Line Items]
Credit Rating	[1]	Baa1
Standard & Poor's [Member] | Bank of America, N.A. [Member]
Derivative [Line Items]
Credit Rating	[1]	A+
Standard & Poor's [Member] | Credit Suisse International [Member]
Derivative [Line Items]
Credit Rating	[1]	A
Standard & Poor's [Member] | Societe Generale [Member]
Derivative [Line Items]
Credit Rating	[1]	A
Standard & Poor's [Member] | Barclays Bank PLC [Member]
Derivative [Line Items]
Credit Rating	[1]	A-
Standard & Poor's [Member] | Citigroup Inc [Member]
Derivative [Line Items]
Credit Rating	[1]	BBB+

[1] As assigned by Standard & Poor’s Corporation (“S&P”) and Moody’s Investors Service, Inc. (“Moody’s”).