Share-based Compensation (Nonvested Restricted Stock) (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) Installment $ / shares shares	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares
Nonvested Awards, Weighted Average Grant Date Fair Value [Roll Forward]
Common shares reserved for stock option and restricted stock grants	5,461,000.000
Restricted Stock [Member]
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 | Installment	8
Nonvested Awards, Number of Shares [Roll Forward]
Nonvested awards, Shares, beginning balance	203,314	188,522	75,265
Nonvested awards, Shares Granted	26,119	132,069	171,781
Nonvested awards, Shares Vested	(101,441)	(108,798)	(52,388)
Nonvested awards, Shares Forfeited	(4,338)	(8,479)	(6,136)
Nonvested awards, Shares, ending balance	123,654	203,314	188,522
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) | $ / shares	$ 25.56	$ 17.13	$ 19.92
Nonvested awards, Granted, Weighted Average Grant Date Fair Value (in dollars per share) | $ / shares	44.79	30.29	16.96
Nonvested awards, Vested, Weighted Average Grant Date Fair Value (in dollars per share) | $ / shares	23.25	17.35	20.35
Nonvested awards, Forfeited, Weighted Average Grant Date Fair Value (in dollars per share) | $ / shares	35.54	17.20	18.91
Nonvested awards outstanding, Weighted Average Grant Date Fair Value, ending balance (in dollars per share) | $ / shares	$ 31.17	$ 25.56	$ 17.13
Unrecognized compensation cost, share-based compensation arrangements | $	$ 3.4
Weighted average period to recognize nonvested awards (in years)	1 year 10 months 2 days
Fair value of shares vested during period | $	$ 2.4	$ 1.9	$ 1.1
Stock compensation expense recognized on restricted grants | $	$ 2.5	$ 1.5	$ 1.5