Share-based Compensation (Nonvested Restricted Stock) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014 Installment	Dec. 31, 2013	Dec. 31, 2012
Nonvested Awards, Weighted Average Grant Date Fair Value [Roll Forward]
Common shares reserved for stock option and restricted stock grants	5,700,000
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rate, initial year (percent)	33.33%
Quarterly award vesting installments after initial year	8
Nonvested Awards, Number of Shares [Roll Forward]
Nonvested awards, Shares, beginning balance	75,265	121,156	145,081
Nonvested awards, Shares Granted	171,781	32,842	73,061
Nonvested awards, Shares Vested	(52,388)	(76,576)	(90,379)
Nonvested awards, Shares Forfeited	(6,136)	(2,157)	(6,607)
Nonvested awards, Shares, ending balance	188,522	75,265	121,156
Nonvested Awards, Weighted Average Grant Date Fair Value [Roll Forward]
Nonvested awards outstanding, Weighted Average Grant Date Fair Value, beginning balance (in dollars per share)	$ 19.92	$ 22.74	$ 20.13
Nonvested awards, Granted, Weighted Average Grant Date Fair Value (in dollars per share)	$ 16.96	$ 15.91	$ 23.26
Nonvested awards, Vested, Weighted Average Grant Date Fair Value (in dollars per share)	$ 20.35	$ 22.56	$ 18.89
Nonvested awards, Forfeited, Weighted Average Grant Date Fair Value (in dollars per share)	$ 18.91	$ 23.42	$ 24.10
Nonvested awards outstanding, Weighted Average Grant Date Fair Value, ending balance (in dollars per share)	$ 17.13	$ 19.92	$ 22.74
Unrecognized compensation cost, share-based compensation arrangements	$ 2,500,000
Weighted average period to recognize nonvested awards (in years)	2 years 1 month 2 days
Fair value of shares vested during period	1,100,000	1,700,000	1,700,000
Stock compensation expense recognized on restricted grants	$ 1,500,000	$ 1,500,000	$ 1,500,000