Common Stock (Performance Share Summary) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance Shares Payout Level	0.00%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance Shares Payout Level	200.00%
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average per share grant date fair value per share of performance shares awarded	$ 34.69		$ 32.74		$ 23.45
Fair value of performance shares vested	$ 849		$ 1,193		$ 628
Performance shares vested - Aggregated Intrinsic Value	1,450	[1]	3,464	[1]	1,032	[1]
Share-based Compensation Expense	1,188	[2]	170	[2]	1,573	[2]
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense	$ 416		$ 59		$ 551
Performance Shares Payout Level	100.00%

[1] Based on a 100% performance level.

[2] Includes adjustments for forfeiture of performance share awards by certain executives.