Stock-Based Compensation - Summary of Employee and Director Share Grant Activity (Details) - Restricted Stock [Member] - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Restricted Stock Grants
Balance at the beginning of the period (in shares)	318,409	291,749	395,360
Granted (in shares)	119,931	174,558	117,370
Released (in shares)	(128,808)	(129,808)	(197,386)
Cancelled (in shares)	(9,947)	(18,090)	(23,595)
Balance at the end of the period (in shares)	299,585	318,409	291,749
Weighted-Average Grant-Date Fair
Balance at the beginning of the period (in dollars per share)	$ 55.75	$ 37.73	$ 26.96
Granted (in dollars per share)	87.61	69.18	49.25
Released (in dollars per share)	50.05	34.86	23.07
Cancelled (in dollars per share)	67.36	44.54	37.19
Balance at the end of the period (in dollars per share)	$ 70.57	$ 55.75	$ 37.73