Business Segments, Concentration of Business, and Credit Risk and Significant Customers (Details 2) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2012	Dec. 31, 2011
Reconciliations of total assets from reportable segments to the condensed consolidated balance sheets
Cash and cash equivalents	$ 84,107	$ 110,247	$ 61,636	$ 263,606
Consolidated total assets	1,275,938	1,068,064
Reportable segments
Reconciliations of total assets from reportable segments to the condensed consolidated balance sheets
Consolidated total assets	989,488	816,807
Unallocated to Segments
Reconciliations of total assets from reportable segments to the condensed consolidated balance sheets
Cash and cash equivalents	84,107	110,247
Unallocated deferred tax assets	31,279	30,662
Other unallocated corporate assets	$ 171,064	$ 110,348