Business Segments, Concentration of Business, and Credit Risk and Significant Customers (Details 2) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012	Dec. 31, 2011
Reconciliations of total assets from reportable segments to the condensed consolidated balance sheets
Cash and cash equivalents	$ 49,126	$ 110,247	$ 114,401	$ 263,606
Consolidated total assets	1,022,115	1,068,064
Reportable segments
Reconciliations of total assets from reportable segments to the condensed consolidated balance sheets
Consolidated total assets	793,298	816,807
Unallocated to Segments
Reconciliations of total assets from reportable segments to the condensed consolidated balance sheets
Cash and cash equivalents	49,126	110,247
Unallocated deferred tax assets	30,206	30,662
Other unallocated corporate assets	$ 149,485	$ 110,348