Summary of Significant Accounting Policies (Details 8) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Accumulated goodwill impairment loss, Beginning balance	$ 253,570	$ 248,625
Goodwill impairment charge	0	4,945	0
Accumulated goodwill impairment loss, Ending balance	$ 253,570	$ 253,570	$ 248,625

Loss recognized during the period that results from the write-down of goodwill after comparing the implied fair value of reporting unit goodwill with the carrying amount of that goodwill. Goodwill is assessed at least annually for impairment.

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+ Details