Equity (Details)	9 Months Ended
	Sep. 30, 2017 USD ($) Plan $ / shares shares
Equity awards [Abstract]
Number of stock-based employee compensation plans | Plan	1
2006 Plan [Member] | Restricted Stock Units (RSUs) [Member]
Restricted stock unit award activity [Roll Forward]
Outstanding, beginning of period (in shares) | shares	875,584
Granted (in shares) | shares	454,513
Vested (in shares) | shares	(413,752)
Forfeited (in shares) | shares	(34,355)
Outstanding, end of period (in shares) | shares	881,990
Weighted-Average Grant Price [Roll Forward]
Outstanding, beginning of period (in dollars per share) | $ / shares	$ 28.94
Granted (in dollars per share) | $ / shares	30.86
Vested (in dollars per share) | $ / shares	20.66
Forfeited (in dollars per share) | $ / shares	28.87
Outstanding, end of period (in dollars per share) | $ / shares	$ 30.39
Aggregate intrinsic value [Abstract]
Outstanding, beginning of period | $	$ 28,754,179
Outstanding, end of period | $	$ 35,676,496
2006 Plan [Member] | Stock Options Member [Member]
Options outstanding [Roll Forward]
Outstanding, beginning of period (in shares) | shares	2,559,331
Granted (in shares) | shares	418,141
Exercised (in shares) | shares	(512,542)
Forfeited (in shares) | shares	(24,625)
Outstanding, end of period (in shares) | shares	2,440,305
Weighted-Average Exercise Price [Roll Forward]
Outstanding, beginning of period (in dollars per share) | $ / shares	$ 22.94
Granted (in dollars per share) | $ / shares	30.85
Exercised (in dollars per share) | $ / shares	19.90
Forfeited (in dollars per share) | $ / shares	27.81
Outstanding, end of period (in dollars per share) | $ / shares	$ 24.88
Aggregate Intrinsic Value [Abstract]
Outstanding, beginning of period | $	$ 25,348,245
Outstanding, end of period | $	$ 37,991,459