Cash and Cash Equivalents and Short-term Investments (Details 3) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012
Gross unrealized losses of cash and cash equivalents and short-term investments
Available-for-sale securities, less than 12 months	$ 18,180
Available-for-sale securities, more than 12 months	535
Available-for-sale securities, continuous unrealized loss position, less than 12 Months, aggregate losses	1,031
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, aggregate losses	194
Available-for-sale equity securities
Gross unrealized losses of cash and cash equivalents and short-term investments
Available-for-sale securities, less than 12 months	17,865
Available-for-sale securities, continuous unrealized loss position, less than 12 Months, aggregate losses	1,030
Available-for-sale debt securities
Gross unrealized losses of cash and cash equivalents and short-term investments
Available-for-sale securities, less than 12 months	315
Available-for-sale securities, more than 12 months	535
Available-for-sale securities, continuous unrealized loss position, less than 12 Months, aggregate losses	1
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, aggregate losses	194
Mortgage-CMO debt securities
Gross unrealized losses of cash and cash equivalents and short-term investments
Available-for-sale securities, less than 12 months	315
Available-for-sale securities, more than 12 months	35
Available-for-sale securities, continuous unrealized loss position, less than 12 Months, aggregate losses	1
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, aggregate losses	2
Asset-backed debt securities
Gross unrealized losses of cash and cash equivalents and short-term investments
Available-for-sale securities, more than 12 months	500
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, aggregate losses	$ 192