Stock-Based Compensation Plans (Schedule of Company's Stock Options Outstanding) (Details) - Stock Options [Member] $ / shares in Units, $ in Thousands	6 Months Ended
Jun. 30, 2018 USD ($) $ / shares shares
Number of shares:
Balance options outstanding, beginning \| shares	38,689
Granted \| shares
Exercised \| shares	(29,689)
Forfeited \| shares
Expired \| shares
Balance options outstanding, end \| shares	9,000
Exercisable, end of period \| shares	9,000
Weighted Average Exercise Price
Balance, beginning \| $ / shares	$ 16.09
Granted \| $ / shares
Exercised \| $ / shares	16.61
Forfeited \| $ / shares
Expired \| $ / shares
Outstanding \| $ / shares	14.35
Exercisable \| $ / shares	$ 14.35
Weighted- Average Contractual Term (years), outstanding	10 months 25 days
Weighted- Average Contractual Term (years), exercisable	10 months 25 days
Aggregate Intrinsic Value, exercised \| $	$ 659,743
Aggregate Intrinsic Value, outstanding \| $	239,040
Aggregate Intrinsic Value, exercisable \| $	$ 239,040

The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.