Summary of Significant Accounting Policies Changes in accounting principles (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other assets	$ 46,142	$ 37,699
TOTAL ASSETS	1,415,554	1,205,239
Convertible senior subordinated notes due 2017 - net	56,518	55,943
Convertible senior subordinated notes due 2018 - net	84,714	84,006
Senior notes - net	294,727	226,099
Liabilities	818,988	660,944
Accounting Standards Update 201503 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other assets		37,699
TOTAL ASSETS		1,205,239
Convertible senior subordinated notes due 2017 - net		55,943
Convertible senior subordinated notes due 2018 - net		84,006
Senior notes - net		226,099
Liabilities		660,944
Scenario, Previously Reported [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other assets		43,870
TOTAL ASSETS		1,211,410
Convertible senior subordinated notes due 2017 - net		57,500
Convertible senior subordinated notes due 2018 - net		86,250
Senior notes - net		228,469
Liabilities		667,115
Scenario, Adjustment [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other assets	$ (7,800)	(6,171)
TOTAL ASSETS		(6,171)
Convertible senior subordinated notes due 2017 - net		(1,557)
Convertible senior subordinated notes due 2018 - net		(2,244)
Senior notes - net		(2,370)
Liabilities		$ (6,171)