Share-Based Compensation - Summary Nonvested Share Activity (Details) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Weighted Average Grant Date Fair Value
Beginning of period (in dollars per share)	$ 6.17	$ 4.72	$ 3.45
Granted (in dollars per share)	30.30	8.24	6.81
Vested (in dollars per share)	5.17	3.90	3.09
Forfeited (in dollars per share)	6.70	6.05	4.77
End of period (in dollars per share)	$ 6.65	$ 6.17	$ 4.72
Number of Non-vested Shares
Beginning of period (in shares)	1,465	1,559	1,592
Granted (in shares)	561	535	564
Vested (in shares)	(486)	(517)	(518)
Forfeited (in shares)	(79)	(112)	(79)
End of period (in shares)	1,461	1,465	1,559