Segments (Details 4) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting Information [Line Items]
Total assets	$ 10,267,807	$ 9,597,278
Domestic [Member]
Segment Reporting Information [Line Items]
Total assets	7,536,285	7,232,177
Foreign [Member]
Segment Reporting Information [Line Items]
Total assets	$ 2,731,522	$ 2,365,101