Stock-Based Employee Benefit Plans - Activity Under Share-Based Compensation Stock Option Plans (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($) $ / shares shares
Outstanding Number of Shares
Outstanding Options, Number of Shares, Beginning Balance | shares	240,493
Options exercised | shares	(53,219)
Options forfeited | shares	(10,193)	[1]
Options expired | shares	(8,480)	[1]
Outstanding Options, Number of Shares, Ending Balance | shares	168,601
Options Weighted Avg Exercise Price
Options Weighted Avg Exercise Price, Beginning Balances | $ / shares	$ 11.62
Options exercised | $ / shares	11.65
Options forfeited | $ / shares	11.61
Options expired | $ / shares	11.74
Options Weighted Avg Exercise Price, Ending Balances | $ / shares	$ 11.61
Options Weighted Avg Contractual Term (Years), Ending Balances	3 years 4 months 28 days
Options Aggregate Intrinsic Value, Ending Balances | $	$ 165,685

[1] For purpose of above table, shares are counted on a fungible basis (i.e., at a higher multiplier than one-for-one) for full value award activity.