XML 64 R53.htm IDEA: XBRL DOCUMENT v3.5.0.2
Convertible Senior Notes Accounting for Convertible Senior Notes (Details) - USD ($)
6 Months Ended
Jun. 30, 2016
Jun. 30, 2015
Dec. 31, 2015
Nov. 30, 2005
May 31, 2005
Debt Instrument [Line Items]          
Interest expense from accretion of discount on convertible senior notes $ 258,000 $ 235,000      
Own-share Lending Arrangement, Shares, Outstanding 1,459,233   1,459,233    
5.875% Convertible Senior Notes Due 2035 [Member]          
Debt Instrument [Line Items]          
Debt Instrument, Face Amount $ 88,780,000   $ 93,280,000 $ 300,000,000.0  
Debt Instrument, Interest Rate, Stated Percentage       5.875% 5.875%
Conversion price for convertible senior notes (in dollars per share) $ 24.61        
3.625% Convertible Senior Notes Due 2025 [Member]          
Debt Instrument [Line Items]          
Debt Instrument, Face Amount         $ 250,000,000.0
Debt Instrument, Interest Rate, Stated Percentage         3.625%