Income Taxes (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Income Taxes [Line Items]
Effective tax rate	39.70%	38.00%	31.00%
Income tax holiday partial expiration year	2013
Unrecognized tax benefit	$ 1,300,000	$ 1,896,000	$ 2,210,000
Unrecognized tax benefit if recognized would reduce effective tax rate in future periods	1,300,000
Liabilities for potential interest and penalties	200,000
Valuation allowance for net operating losses, specific capital losses and foreign tax credit carryforwards	1,300,000	200,000
Income taxes paid	31,700,000	24,900,000	23,700,000
Minimum [Member]
Income Taxes [Line Items]
Net operating loss carry forward expiration year	2012
Decrease in unrecognized tax benefit	600,000
Maximum [Member]
Income Taxes [Line Items]
Net operating loss carry forward expiration year	2029
Unrecognized tax benefit	$ 1,300,000