Derivative Financial Instruments (Company's Derivative Instruments of Interest Rate Swaps) (Details) (LIBOR [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015
Interest Rate Swap One [Member]
Derivative [Line Items]
Date entered	2011-12
Notional amount	$ 175,000
Fixed interest rate paid	1.60%	[1]
Variable interest rate received	1-month LIBOR
Effective date	2014-02
Expiration date	2017-02
Interest Rate Swap Two [Member]
Derivative [Line Items]
Date entered	2014-04
Notional amount	100,000
Fixed interest rate paid	1.80%	[1]
Variable interest rate received	1-month LIBOR
Effective date	2014-07
Expiration date	2019-07
Interest Rate Swap Three [Member]
Derivative [Line Items]
Date entered	2014-05
Notional amount	50,000
Fixed interest rate paid	2.344%	[1]
Variable interest rate received	1-month LIBOR
Effective date	2015-10
Expiration date	2020-10
Interest Rate Swap Four [Member]
Derivative [Line Items]
Date entered	2014-05
Notional amount	25,000
Fixed interest rate paid	2.326%	[1]
Variable interest rate received	1-month LIBOR
Effective date	2015-10
Expiration date	2020-10
Interest Rate Swap Five [Member]
Derivative [Line Items]
Date entered	2014-05
Notional amount	50,000
Fixed interest rate paid	2.35%	[1]
Variable interest rate received	1-month LIBOR
Effective date	2015-10
Expiration date	2020-10
Interest Rate Swap Six [Member]
Derivative [Line Items]
Date entered	2014-05
Notional amount	$ 50,000
Fixed interest rate paid	2.35%	[1]
Variable interest rate received	1-month LIBOR
Effective date	2015-10
Expiration date	2020-10

[1] Plus applicable margin.