Marketable Securities (Maturities of Marketable Securities) (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Marketable Securities [Abstract]
Amortized Cost, Due within one year	$ 1,508
Fair Value, Due within one year	1,489
Amortized Cost, Due after one year through five years	48,397
Fair Value, Due after one year through five years	48,438
Amortized Cost, Due after five years through ten years	19,813
Fair Value, Due after five years through ten years	21,221
Amortized Cost, Due after ten years	1,998
Fair Value, Due after ten years	1,999
Amortized Cost, Equity securities	1,136
Fair Value, Equity securities	9,447
Available-for-sale Securities, Amortized Cost Basis, Total	72,852	80,101
Available-for-sale Securities, Fair Value, Total	$ 82,594	$ 89,348