Debt Convertible Notes (Details) - USD ($)		12 Months Ended
	Nov. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 20, 2011	Dec. 15, 2011
Debt Instrument [Line Items]
Interest Paid		$ 32,934,000	$ 32,278,000	$ 33,266,000
Convertible Debt		$ 57,500,000	$ 57,500,000
Common Stock, Shares Authorized		60,000,000	60,000,000
Convertible Debt, Principle Amount to be Exchanged		$ 1
Convertible Debt, Principal Amount to be Received		$ 1
Convertible Notes Due in 2017 [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount						$ 57,500,000
Convertible debt issued at a percentage of face value, percentage					100.00%
Maturity date		Dec. 15, 2017
Stated interest rate on debt		7.00%					7.00%
Interest Paid		$ 4,025,000	$ 4,025,000	$ 4,025,000
Conversion rate, shares per principal amount of convertible notes, shares		97.2384
Conversion rate, principal amount of convertible notes for shares, principal amount		$ 1,000
Conversion price per share		$ 10.28
Date at which holders may convert their convertible notes at their option		preceding June 15, 2017
Scenarios in Which Holders of Convertible Notes can Convert, Conversion Period Following Measurement Period		5 days
Measurement Period, Consecutive Trading Days.		5 days
Trading price per note for each day of that measurement period		less than 98%
Period of Consecutive Trading Days		30 days
Last reported sale price of the company's common stock		equal to or greater than 130%
Date on which convertible notes will be convertible		Jun. 15, 2017
Upon fundamental change, percentage of principal amount of convertible notes the company would be required to repurchase		100.00%
Call of convertible notes for redemption		Dec. 20, 2015
Scenarios for call of Convertible Notes, minimum sale price of common stock as a percentage of conversion price		135.00%
Scenarios for call of Convertible Notes, consecutive trading days		30 days
Scenarios for call of Convertible Notes, redemption price		100.00%
Convertible Notes Due in 2019 [Member]
Debt Instrument [Line Items]
Maturity date		Dec. 31, 2019
Stated interest rate on debt		5.25%
Convertible Debt Exchanged, Percent		90.00%
Conversion price per share		$ 2.25
Convertible Notes Exchanged, Amount		$ 51,600,000
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt, Weighted Average Interest Rate		2.70%	3.08%	2.71%
Maturity date	Dec. 15, 2015	Dec. 10, 2019
Minimum | Convertible Notes Due in 2017 [Member]
Debt Instrument [Line Items]
Debt Instrument, Convertible, Threshold Trading Days		20 days
Scenarios for call of Convertible Notes, period of trading days		20 days